Download - 8-Optical Power Calculation Training
![Page 1: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/1.jpg)
HUAWEI
WDM OPTICAL POWER
MANAGEMENT TRAINING
© 2013 Huawei Technologies Co.,Ltd.
![Page 2: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/2.jpg)
All Rights Reserved No part of this manual may be reproduced or transmitted in any form or by any means without prior written consent of Huawei technologies Co., Ltd
Trademarks
HUAWEI, C&C08, EAST8000, HONET, ViewPoint, Intess, ETS, DMC, TELLIN, InfoLink,
Netkey, Quidway, SYNLOCK, Radium, M900/M1800, TELESIGHT, Quidview, Musa, Airbridge, Tellwin, Inmedia, VRP, DOPRA, iTELLIN, HUAWEI Optix, C&C08 iNET, NETENGINE, Optix, SoftX, iSite, U-SYS, iMUSE, OpenEye, Lansway, SmartAX are trademarks of Huawei Technologies Co., Ltd.
All other trademarks mentioned in this manual are the property of their respective holders.
Notice The information in this manual is subject to change without notice, every effort has been made in the preparation of this manual to ensure accuracy of the contents, but all statements, information, and recommendations in this manual do not constitute a warranty of any kind, express or implied.
![Page 3: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/3.jpg)
www.huawei.com
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved.
OptiX WDM Product Optical Power Calculation
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page1
Foreword
� When commissioning or planning the WDM network, we
need to calculate the optical power. This Course will
introduce the method of OptiX WDM Product power
calculation.
1
![Page 4: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/4.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page2
About This Course
� This Course is based on:
� OptiX BWS 1600G Hardware Description
� OptiX Metro 6100 Hardware Description
� OptiX OSN 6800 Hardware Description
� OptiX OSN 6800 Commissioning Guide
� OptiX OSN 68003800 Optical Power Calculation
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page3
Objectives
� Upon completion of this course, you will be able to:
� Illustrate the relation of each reference point.
� List the common indices on optical power calculation.
� Calculate the optical power.
2
![Page 5: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/5.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page4
Contents
1. Basics
2. Power Calculation
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page5
Contents
1. Basics
1.1 Review of the signal flow
1.2 Basic Concepts
3
![Page 6: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/6.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page6
Review of Signal Flow
OTUM40
M40
M40
D40
F
I
USC1
OA
SC2
OTU
OTU
OTU
OA OA
OA
F
I
U
F
I
U
F
I
U
OA
M40
D40
OTU
OTU
OTU
OTU
M40
M40OA
OTM1OTM1 OLAOLA OTM2OTM2
SC1
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page7
Review of Signal Flow (Cont.)
F
I
U
F
I
U
SC2
MR2
OA
OAMR2
MR2
MR2
OA
OA
FOADMFOADMOTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
4
![Page 7: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/7.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page8
Review of Signal Flow (Cont.)
F
I
U
F
I
U
SC2
ROAM
OA
OA OA
OA
ROADM:ROADM:(ROAM)(ROAM)
ROAM
M 4 0D40M 4 0D40
OTU
OTU
OTU
OTU
…… ……
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page9
Review of Signal Flow (Cont.)
F
I
U
OA
OA
WSD9 WSM9
WSM9 WSD9
OA
OA
F
I
U
M 4 0M40 M 4 0D40
M40 D40 M40 M40
ROADM:ROADM:(WSD9+WSM9)(WSD9+WSM9)
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
……
…… ……
……
5
![Page 8: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/8.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page10
Review of Signal Flow (Cont.)
F
I
U
OA
OA
WSD9 RMU9
RMU9 WSD9
OA
OA
F
I
U
M 4 0D40
M40 D40
ROADM:ROADM:(WSD9+RMU9)(WSD9+RMU9)
MR4
MR4
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
OTU
……
…… ……
……
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page11
Units
� mW
the unit of optical power
� dBm
the unit of optical power
� dB
the unit of gain or attenuation
of optical power
Basic Concept
P(mW)
1(mW)
Calculation
P1(dBm)
P2(dBm)
P1(mW)
P2(mW)
� P (dBm) =10lg
� P (dB)=10lg =10lg
� -10dBm = mW
� 0dBm = mW
� 10dBm= mW
� 20dBm = mW
� 20dBm-10 =10dBm
6
![Page 9: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/9.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page12
Formula
The situation of N wavelengths
Ptotal (dBm) =Psingle (dBm) +10lgN(dB)
P1
Ptotal
P2
Suppose P1=P2=Psingle
Ptotal (mW) = P1 (mW) + P2 (mW)
Ptotal (dBm) =Psingle (dBm) +10lg2(dB)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page13
Tips on Optical Power Calculation� Optical power values expressed in dBm can be subtracted from each other but
cannot be added to each other.
� Optical power values expressed in dBm can be added to each other only after they are
converted into values expressed in mW.
� The result of one value expressed in dBm minus another value expressed in dBm is
expressed in dB. The result of one value expressed in dBm minus another value
expressed in dB is expressed in dBm. For example: 5dBm-3dBm=2dB; 5dBm-3dB=
2dBm.
P (??) = P1 (dBm) - P2 (dBm)The optical power values expressed in dBm can be added to or subtracted from
each other only after they are converted into values expressed in mW.
P (dB) =10lg -10lg = 10lgP1(mW)
1(mW)
P2(mW)
1(mW)
P1(mW)
P2(mW)
P (dB) = P1 (dBm) - P2 (dBm)
7
![Page 10: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/10.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page14
Tips on Optical Power Calculation (2)� The following are some values that are frequently used during calculation of total
multiplexed optical power:
10lg2=3 10lg4=2*10lg2=6 10lg32=5*10lg2=15
10lg10=10 10lg40=10lg(4*10)=10lg4+10lg10=16
� Quiz: If the nominal single-wavelength optical power of an 80-channel WDM
network is +4 dBm, what is the total multiplexed output optical power expressed in
dBm?
� Pmultiplexed = 10lg(80*Psingle (mW)) = Ptotal (dBm) + 10lg(8*10)
= Psingle (dBm) + 10lg8 + 10lg10
= 4 + 9 + 10 (dBm) = 23 (dBm)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page15
Common Specifications� Optical power calculation involves three common specifications: insertion loss, optical amplifier
unit parameters, and OTU parameters.
� For the common specifications, you can refer to the following documentation:
� Approach 1: Refer to section "Technical Specifications" in the Product Description manual.
� Approach 2: Refer to Appendix D "Quickfinder of Board Specifications and Functions" in the
Hardware Description manual.
� Approach 3: Refer to section "Board Specifications" in the board description chapter in the
Hardware Description manual.
� For the OAU parameters, you can also refer to the Commissioning Guide.
The manuals of WDM products are available on Huawei Support website. You can obtain them
from the following directory:
8
![Page 11: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/11.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page16
Insertion Loss
� The loss of output optical power after the optical signals of
each channel pass through the corresponding channels.
Passive component
PoutPin
Insertion Loss (IL) = Pin–Pout
Unit: dB
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page17
Common Specifications
9
![Page 12: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/12.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page18
Common Specifications� Insertion loss of DCMs is a critical specification for optical power calculation. The DCM
insertion loss specifications of each WDM product are provided in section "Technical
Specifications" in the Product Description manual of the product.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page19
OAU Parameters � Input optical power ①
� Output optical power ②
� Maximum single-wavelength output optical power ③
� Typical single-wavelength output optical power ④
� Gain
OA
Pout ②Pin ①
Pout ③
Total gain of the OAU (dB) = Pout ② (dBm) – Pin ① (dBm)
Single-wavelength gain (dB)= Pout ③ (dBm) – Pin ④ (dBm)
Pin ④
10
![Page 13: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/13.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page20
Common Specifications� For OAU specifications such as the input and output optical power range
and gain range, refer to the Hardware Description manual.
Note: For OAU specifications, you can also refer to Appendix D "Quickfinder of Board
Specifications and Functions" in the Hardware Description manual.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page21
Common Specifications� For OAU specifications such as the maximum single-wavelength output optical power and typical
single-wavelength output optical power, refer to section "Commissioning the Optical Power of the
EDFA" in the Commissioning Guide.
11
![Page 14: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/14.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page22
Common SpecificationsSection "Commissioning the Optical Power of the EDFA" in the Commissioning Guide
Note: For OAU specifications, you can also refer to Appendix D "Quickfinder of Board Specifications and Functions" in the Hardware
Description manual.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page23
Characteristics of OTU
� Mean Launch Power
� Receiver sensitivity: A
� Receiver overload: B
Recommended Receiving Power Range: A+3(dBm) ~ B-5(dBm)
The preceding specifications vary with the type of WDM- and client-side
optical modules on the OTU and the transmission distance. For the board
specifications of a WDM product, refer to section "Board Specifications" in
the Hardware Description manual of the product.
12
![Page 15: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/15.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page24
Common Specifications
� Example of LSX
board
specifications
applied to the
OptiX OSN 6800
� The table on the
right shows the
specifications of
the optical module
on the client side.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page25
Common Specifications
� Example of LSX
board
specifications
applied to the
OptiX OSN 6800
� The table on the
right shows the
specifications of
the optical module
on the WDM side.
Note: For board specifications, you can also refer to Appendix D "Quickfinder of Board Specifications and Functions" in the Hardware Description manual.
13
![Page 16: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/16.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page26
Summary
� This chapter describes the following common specifications
used in optical power calculation of boards of WDM
products:
� Board insertion loss
� OAU parameters
� OTU parameters
� Section "Technical Specifications" in the Product
Description manual of each WDM product describes the
board parameters of the product.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page27
Questions
� What are the units related to optical power?
� The conversion between mW and dBm?
� If the input power of each channel is –4 dBm, what’s the value of
input power for 40 wavelengths?
14
![Page 17: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/17.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page28
Contents
1. Basics
2. Power Calculation
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page29
Contents
2. Power calculation
2.1 Power calculation of OSC
2.2 Power calculation of Main Path
15
![Page 18: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/18.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page30
� Typical Launch Power
SC2: 0 ~ -4
SC1: 2 ~ 4.5dBm
� Sensitivity of SC1/SC2: -48dbm
� Receiving Power=Launch Power - Loss of Fiber - 2•IL of FIU.
Power Calculation of OSC
TM RM
SC1/2SC1 SC1/2SC1
F
I
U
F
I
URM TM
2dBm
40km (12dB)
IL:1.5dB
0.5dBm -11.5dBm -13dBm
IL:1.5dB
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page31
Main-Path Optical Power Calculation—Basic Concepts
� OAU gain range:
� A gain range that depends on the hardware performance of the OAU. For the value of the
gain range, refer to the product manual.
� Typical gain of the OAU:
� The result of the nominal single-wavelength output optical power minus the nominal single-
wavelength input optical power after the input and output optical power of the OAU are
adjusted to the nominal values.
� Configurable gain range of the OAU:
� In actual applications, the configurable gain range of the OAU does equal the OAU gain
range. The configurable gain range of the OAU equals the OAU gain range minus the
passthrough insertion loss between the TDC and RDC optical interfaces. This formula
applies to the application scenario where a DCM is connected between the TDC and RDC.
For example, if the gain range of an OAU is 20–31 dB and the insertion loss between the
TDC and RDC is 5 dB queried on the T2000, then the configurable gain range of this OAU
is 20–26 dB (actually 15–26 dB. Because the gain value smaller than 20 dB is not
configurable on the T2000, the lower limit of the gain range does not change).
16
![Page 19: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/19.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page32
Main-Path Optical Power Calculation—Basic ConceptsSteps:
� Adjust the VOA to obtain –16 dBm nominal
single-wavelength input optical power of the
OAU. Set the gain to the typical gain value 20
dB to obtain +4 dBm nominal maximum
single-wavelength output optical power of the
OAU.
OAU101
PA BA③
⑤
DCM(B)
� If the input optical power fails to be adjusted to the nominal value, set the gain of the OAU to obtain the nominal output optical power. In this case, the configurable gain range of the OAU need be calculated. The configurable gain range of the OAU equals the OAU gain range minus the passthrough insertion loss between the TDC and RDC optical interfaces. For example, if the insertion loss between the TDC and RDC is 5 dB (it approximates the DCM insertion loss plus the fiber connector insertion loss) queried on the T2000 and the gain range of an OAU is 20–31 dB, then the configurable gain range of this OAU is 20–26 dB.
� If the single-wavelength output optical power can reach up to only –20 dBm, after the configurable gain range is calculated, 24 dB gain is required if the single-wavelength output optical power is the nominal single-wavelength output optical power plus 4 dBm. The 24 dB gain is within the configurable gain range 20–26 dB of the OAU. Hence, set the gain of the OAU to 24 dB.
� In the rare case that the gain value to be set is beyond the configurable gain range, it indicates that the client fiber attenuation is much larger than the designed value. In this case, stop the commissioning and notify the customer to solve the fiber attenuation problem.
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page33
Station A Station B
40km(12dB)
� The distance between station A and station B: 40km, line attenuation: 12dB.
� The same board configuration of station A and station B :
� Transmitting end: OBU101.
� Receiving end: OAU101.
OTM OTM
� Network topology
Power Calculation of Main Path - OTM
17
![Page 20: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/20.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page34
To station B
② ③ ④
OTU
M40
M40 OBU101
F
I
U
① ⑤
① Suppose Typical Launch Power of OTU: -2dBm.
② Min. insertion loss of VOA : 2dB.
③ IL of M40: 6.5dB.
④ OBU101 nominal individual channel input/output Power-20/0dBm, typical gain: 20 dB.
⑤ IL of FIU:1.5dB.
VOA
� Signal flow and related indices at the transmitting side of station A
Power Calculation of Main Path - OTM
Notes: The VOA is commonly placed after the output interface of each OTU board in the signalflow for Metro/NG WDM. The VOA is commonly placed after the M40 for the LH-DWDM
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page35
② ③ ④
OTU
M40
M40
F
I
U
①
To station B
� Typical optical power of the reference points at the transmitting side
of station A – Single Channel
-2dBm -20dBm 0dBm -1.5dBm
Power Calculation of Main Path - OTM
OBU101
18
![Page 21: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/21.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page36
② ③ ④
M40
M40
F
I
U
①
� Ptotal (dBm)====Psigle (dBm) + 10lgN (dB)
OTU
OTU
-2dBm -20+10lgN 0+10lgN -1.5+10lgN
To station B
� Typical optical power of the reference points at the transmitting side
of station A – Multiplex Channels
Power Calculation of Main Path - OTM
OBU101
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page37
Station A Station B
� The launched optical power of station A : -1.5+10lgN(dBm).
� Attenuation of the line fiber: 12dB.
� The receiving optical power of station B: -13.5+10lgN(dBm).
OTM OTM40km(12dB)
-1.5+10lgN -13.5+10lgN
Power Calculation of Main Path - OTM
� Network topology and the line optical power
19
![Page 22: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/22.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page38
① IL of FIU:1.5dB.
② Min. IL of VOA : 2dB.
③ OAU101 nominal individual channel input/output Power -16/4dBm, typical gain: 20 dB.
④ IL of D40: 6.5dB.
⑤ Typical receiving optical power of OTU: -16dBm (APD), -9dBm (PIN).
① ②
M40
D40F
I
U
③ ④ ⑤
M40
D40
OTU
OTU
Fixed attenuator
-13.5+10lgN
� Signal flow and related indices at the receiving side of station B
Power Calculation of Main Path - OTM
From station A
OAU101
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page39
� If the input optical power of OAU is lower than the nominal power, VOA should be
removed.
④Psingle=Ptotal - 10lgN - IL of D40.
① ②
From station A
M40
D40OPU03
F
I
U
③ ④
M40
D40
OTU
OTU
� Typical optical power of the reference points at the receiving side
of station B-13.5+10lgN -17+10lgN 4+10lgN -2.5dBm
Power Calculation of Main Path - OTM
OAU101
20
![Page 23: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/23.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page40
Power Calculation of Main Path - OLA
Station A Station C
OLAOTM OTM
Station B
40km(12dB)
� OBU103 is used at the transmitting side of station A & C.
� OAU101 is used in station B.
B
B
B DCM-B
� Network topology
60km(18dB)
+4+10lgN -11+10lgN
-1+10lgN-19+10lgN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page41
OAU101
PA BAFrom station A
F
I
U
F
I
U
① ②
④
③ ⑤ ⑥
DCM(B)
� Typical optical power of the reference points from station A to station C
③ ⑤ OAU101 nominal individual channel input/output power: -16/+4dBm, gain range: 20~31dB.
④ IL of DCM(B): 5dB. ① ⑥ IL of FIU: 1.5dB.
Actual gain of OAU101 is 20dB.
-11+10lgN -16+10lgN +4+10lgN +2.5+10lgN
Power Calculation of Main Path - OLA
To station C
21
![Page 24: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/24.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page42
� Please calculate the optical power of each reference point① ② from station C to station A.
F
I
U
F
I
U①②
OAU101
BA
DCM(C)
PA
� Is it necessary to put VOA before OAU101?
� What is the actual gain of OAU101?
-20+10lgN
Questions
From station C
To station A
-21.5+10lgN
+4+10lgN
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page43
Station A Station C
FOADMOTM OTM
Station B
50km(15dB)
� OBU103 is used at the transmitting side of station A & C.
� OAU101/OBU103 is used at the station B.
� Two MR2 is used in station B.
B
B DCM-B
� Network topology
80km(24dB)
+4+10lgN -11+10lgN
Power Calculation of Main Path - FOADM
22
![Page 25: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/25.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page44
③ ⑤ OAU101 nominal individual channel input/output Power -16/+4dBm,
gain range:20~31dB.
④ IL of DCM(B): 5dB. ①⑩ IL of FIU: 1.5dB. ⑥⑧ IL of MR2: 1dB.
⑨OBU103 nominal individual channel input/output Power -19/4dBm.
① ② ③
④
⑤ ⑥ ⑦ ⑧ ⑨ ⑩
OAU101
PA BA
F
I
U
F
I
U
DCM(B)
MR2MR2
OTU
OBU103
� Typical optical power of the reference points from station A to station C
OTU
OTU
OTU
-11+10lgN
Power Calculation of Main Path - FOADM
From station A
To station C
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page45
①
②
③
④
⑤ ⑥ ⑦ ⑧ ⑨ ⑩
OAU101
PA BA
F
I
U
F
I
U
DCM(B)
MR2MR2
OTU
VOA
OBU103
OTU
OTU
OTU
-11+10lgN
-16+10lgN +4+10lgN -19+10lgN 4+10lgN
2.5+10lgN
Power Calculation of Main Path - FOADM
� Typical optical power of the reference points from station A to station C
From station A
To station C
+2.5
23
![Page 26: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/26.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page46
Station A Station C
ROADMOTM OTM
Station B
50km(15dB)
� OBU103 is used at the transmitting side of station A & C.
� OAU101/OBU103 is used at the station B.
� Two ROAM is used in station B.
B
B DCM-B
� Network topology
80km(24dB)
4+10lgN -11+10lgN
Power Calculation of Main Path - ROADM
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page47
③ ⑤ OAU101 nominal individual channel input/output Power -16/+4dBm,
gain range:20~31dB.
④ IL of DCM(B): 5dB. ①⑨ IL of FIU: 1.5dB. ⑩ IL of D40: 6.5dB.
⑥⑦ IL of ROAM: Mx-OUT:9dB, IN-DM:7dB, EXPI-OUT:14dB, IN-EXPO:3dB.
⑧ OBU101 nominal individual channel input/output Power -19/4dBm.
① ② ③
④
⑤ ⑥ ⑦ ⑧ ⑨
OAU101
PA BA
F
I
U
F
I
U
DCM(B)
ROAM
OTU
OBU101
� Typical optical power of the reference points from station A to station C
OTU
OTU
OTU
-13+10lgN
Power Calculation of Main Path – ROADM 1
From station A
To station C
ROAM
D40 ⑩
24
![Page 27: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/27.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page48
①
②
③
④
⑤ ⑥ ⑦
OAU101
PA
F
I
U
F
I
U
DCM(B)
OBU103
-11+10lgN
-16+10lgN +4+10lgN
-3+10lgM
+4+10lgN
+2.5+10lgN
� Typical optical power of the reference points from station A to station C
From station A
To station C
ROAM
OTU
OTU
OTU
OTU
ROAM
D40 ⑩
BA
⑧ ⑨
+1+10lgN’
-19+10lgN
Power Calculation of Main Path – ROADM 1
-9.5dBm
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page49
③⑤ OAU1 nominal individual channel input/output Power -16/+4dBm, gain range:20~31dB.
④ IL of DCM(B): 5dB. ①⑨ IL of FIU: 1.5dB. ⑩ IL of D40: 6.5dB, IL of M40V: 8dB.
⑥ IL of WSD9: 8dB(IN-DMx,IN-EXPO).
⑦ IL of RMU9: 8.5dB(EXPI-OUT)
⑧ OBU103 nominal individual channel input/output Power -19/4dBm.
① ② ③
④
⑤ ⑥ ⑦ ⑧ ⑨
OAU101
PA BA
F
I
U
F
I
U
DCM(B)
WSD9
OTU
OBU103
� Typical optical power of the reference points from station A to station C
OTU-11+10lgN
Power Calculation of Main Path – ROADM 2
From station A
To station C
RMU9
D40 ⑩
OTU
OTU
M40
25
![Page 28: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/28.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page50
①
②
③
④
⑤ ⑥ ⑦
OAU101
PA
F
I
U
F
I
U
DCM(B)
OBU103
-11+10lgN
� Typical optical power of the reference points from station A to station C
From station A
To station C
BA
⑧ ⑨
Power Calculation of Main Path – ROADM 2
WSD9
OTU
OTU
RMU9
D40 ⑩
-16+10lgN +4+10lgN -19+10lgN
4+10lgN
2.5+10lgN
OTU
OTU
M40
-10.5dBm-4+10lgM
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page51
③⑤ OAU101 nominal individual channel input/output Power -16/+4dBm,
gain range:20~31dB.
④ IL of DCM(B): 5dB. ①⑨ IL of FIU: 1.5dB. ⑩ IL of D40/M40: 6.5dB.
⑥ IL of WSD9: 8dB(IN-DMx,IN-EXPO). ⑦ IL of WSM9: 8dB(AMx-OUT,EXPI-OUT).
⑧ OBU101 nominal individual channel input/output Power -19/4dBm.
① ② ③
④
⑤ ⑥ ⑦ ⑧ ⑨
OAU101
PA BA
F
I
U
F
I
U
DCM(B)
WSD9
OTU
OBU103
� Typical optical power of the reference points from station A to station C
OTU
OTU
OTU-11+10lgN
Power Calculation of Main Path – ROADM 3
From station A
To station C
WSM9
D40 ⑩M40
26
![Page 29: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/29.jpg)
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page52
� Please calculate the optical power of each reference point (40 channels)
Questions
① ② ③
⑥F
I
U
F
I
U
OBUC01
-12+10lgN
From station A
To station C
⑧
⑨
WSMD4
OTU
OTU
OTU
OTU
D40⑤
M40
OAU101 WSMD4
④
-4
⑦
⑦ Optical power of adding wavelength.
⑧ Optical power of passing through.
⑩
Copyright © 2013 Huawei Technologies Co., Ltd. All rights reserved. Page53
Summary
� OSC Power Calculation
� OTM Power Calculation
� OLA Power Calculation
� FOADM Power Calculation
� ROADM(ROAM) Power Calculation
� ROADM(WSD9+RMU9) Power Calculation
� ROADM(WSD9+WSM9) Power Calculation
27
![Page 30: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/30.jpg)
Thank youwww.huawei.com
28
![Page 31: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/31.jpg)
1
OptiX WDM Product Optical Power
Calculation
P1
Welcome to this course on optical power calculation of OptiX WDM products.
In a WDM analog system, it's well known that optical power, optical signal-to-noise
ratio (OSNR), dispersion, and nonlinearity are four critical factors that influence the quality
of signals (QoS). Among these four factors, optical power is the most critical. During
deployment and maintenance of WDM equipment, the optical power of the equipment
must be calculated to ensure successful deployment and troubleshooting.
This course describes the method of calculating the optical power of OptiX WDM
products.
P2
This course is developed on the basis of the PowerPoint document OptiX OSN
3800&6800 Optical Power Calculation, with reference to the OptiX OSN 6800 Intelligent
Optical Transport Platform Commissioning Guide, OptiX OSN 6800 Intelligent Optical
Transport Platform Hardware Description, OptiX BWS 1600G Product Hardware
Description, and OptiX Metro 6100 Product Hardware Description. Should you have any
doubts on any specification or information mentioned in this course, refer to the
corresponding product manuals.
P3
Studying this course enables you to master the following knowledge:
- The relationship between the reference points in the signal flows of a WDM system.
- The common specifications for optical power calculation.
- Method of calculating the optical power at each reference point, with which you can
correctly calculate the optical power of a WDM product during deployment and
maintenance of the product.
P4
This document is organized into two chapters. Chapter 1 "Basic Knowledge"
describes the basic concepts of and tips for optical power calculation. Chapter 2 "Optical
Power Calculation" illustrates some examples to describe the method of optical power
calculation of WDM products in various networking modes.
![Page 32: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/32.jpg)
2
P5
Let's start from Chapter 1. Chapter 1 is organized into two parts. Part 1 describes the
signal flows of WDM products; part 2 describes the basic concepts involved in optical
power calculation.
P6
Let's take a look at this networking mode. It is a common OTM-OLA-OTM networking
mode for WDM products. The signal flows in this networking mode are set forth below.
Signal flow from west to east: One or more wavelengths are added through one ore
more OTU boards at the OTM1 node (in the case of multiple OTUs, the wavelength added
through each OTU is different from the wavelengths added through the other OTUs). The
VOA for each OTU adjusts the optical power of the wavelength added through this OTU.
Then, the M40 board multiplexes the added wavelengths. The OA amplifies the
multiplexed optical signals so that the signals can travel over a long haul. At last, the FIU
board multiplexes the service signals with the OAM overhead signals. The multiplexed
signals travel towards east over the optical cable. This is the internal signal flow of a single
OTM as an optical NE (ONE).
The signals of the OTM1 node travel to the OLA node. The west FIU board at the OLA
node separates the overhead signals from the service signals. The SC2 board receives
and processes the overhead signals, and the VOA adjusts the optical power of the service
signals. Then, the OA unit further amplifies the optical power of the service signals. The
amplified optical service signals continue to travel eastwards to the east FIU board at the
OLA node. On the east FIU board, the service signals are multiplexed with the overhead
signals processed by the SC2 board. The multiplexed signals are fed to the optical cable
and continue to travel eastwards.
The signals sent from the OLA node travel over the optical cable to the downstream
OTM2 node. The west FIU board at OTM2 separates the overhead signals from the
service signals. The overhead signals travel to the SC1 board for processing. Because the
service signals travel over a long-haul optical cable, the attenuation of the service signals
is large. Hence, the OA must be used to amplify the service signals. Then, the D40
demultiplexes the multiplexed service signals into multiple wavelength signals. Each OTU
receives one wavelength. In addition, to ensure that the received optical power of the OTU
is within the proper range, the WDM-side IN optical interface of each OTU must be added
with a fixed optical attenuator.
At this point, the signal flow from the OTM1 node to the OTM2 node is complete. The
signal flow from OTM2 to OTM1 reverses the signal flow from OTM1 to OTM2.
P7
Now let's take a look at the internal signal flow of an FOADM node. The FOADM node
refers to a fixed optical add/drop multiplexer node. The overhead signal flow of service
signal propagation before the OA board at the FOADM node are the same as those at the
![Page 33: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/33.jpg)
3
OLA node, which are omitted in this slide. Let's find out the differences between this slide
and the last slide.
The OA board amplifies the service signals. Then, the amplified service signals enter
the MR2 board for demultiplexing. The MR2 is a typical FOADM board. The FOADM
board serves to separate one or more wavelengths from the service signals and drop the
wavelength(s) from the local client equipment. The other wavelengths of the service
signals pass through the FOADM board and travel to the downstream. The MR2, as its
name implies, serves to separate two wavelengths from the service signals and drop the
two wavelengths from the local client equipment. The other wavelengths of the service
signals pass through the MR2 and travel to the downstream. In addition, multiple FOADM
boards can be cascaded, as shown in the figure in this slide. The second MR2 can further
separate two wavelengths from the wavelengths passed through the first MR2 and drop
the two wavelengths to the local client equipment. The remaining wavelengths pass
through the second MR2 and travel to the downstream. The local OTU board receives the
two wavelengths dropped from the second MR2. To ensure that the received optical
power of the OTU is within the proper range, the WDM-side IN optical interface of each
OTU must be added with a fixed optical attenuator.
The process of wavelength adding reverses that of wavelength dropping. The
principles of the two processes are the same. Not that to ensure that the optical power of
each added wavelength in the OA unit is a proper value, the OUT optical interface of each
OTU must be added with a VOA for optical power adjustment.
P8
Now let's take a look at the internal signal flow of an ROADM node. The ROADM
node refers to a reconfigurable optical add/drop multiplexer node. Compared with the
FOADM node, the ROADM node is advantageous in dynamic grooming of added/dropped
wavelengths from/to the local client equipment. The ROADM node selects different
wavelengths that travel towards different directions, whereas the FOADM node can select
only one fixed wavelength and grooms it towards one direction. Hence, the wavelength
grooming of the FOADM node is not flexible. Generally, the ROADM node can be formed
in three networking modes. Firstly, let's study the first networking mode of the ROADM
node, in which the ROADM node uses two ROAM boards. The signal flow in this
networking mode is set forth below.
See the following figure. Two ROAM boards are used together with the D40 board to
add/drop, pass through, and block a maximum of 40 service wavelengths. This realizes
the dynamic grooming of intra-ring service wavelengths.
In the wavelength dropping direction, the multiplexed optical signals received from
west are accessed to the main-path optical signals through the IN optical interface on the
west ROAM board. The west ROAM board evenly splits the main-path multiplexed optical
signals into two channels of signals. One of the two channels of signals is dropped to the
local D40 and then is output to the local OTU board. The other channel of signals passes
through the west ROAM board and travels to the east ROAM board.
![Page 34: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/34.jpg)
4
In the wavelength adding direction, the optical signals sent from the local OTU board
directly travel to the 40 AM optical interfaces on the west ROAM board for multiplexing.
The west ROAM board can also multiplex the multiplexed optical signals received from
west with the multiplexed optical signals that pass through the east ROAM board, and
outputs the final multiplexed signals to the west optical amplifier board. The west optical
amplifier board amplifies the signals and sends them to the line. Note that during
multiplexing of the 40 channels of added optical signals with the signals that travel from
the upstream, a 2×1 optical switch on the west ROAM board can select from between
each monochrome wavelength that travels from the upstream and each wavelength that is
added from the local client equipment. This realizes the flexible selection between
passthrough and adding of wavelengths.
P9
Then, let's study the second networking mode of the ROADM node, in which the
ROADM node uses the WSD9+WSM9 board combination. These two boards are the
WSS board. The WSS board is used to drop (or add) any wavelength through any output
(or input) optical interface. In addition, the WSS board can demultiplex the received color
optical signals into any combination of wavelengths and outputs them through arbitrary
interfaces. This realizes the grooming between multiple wavelengths on the optical
multiplex section.
A single wavelength or a channel of multiplexed signals to be dropped to the local
client equipment is output through a wavelength dropping interface on the WSD9. In the
case of dropping a channel of multiplexed signals, the D40 board demultiplexes this
channel of multiplexed signals into single wavelengths and sends them to the local client
equipment through OTUs. In the case of dropping a single wavelength, the signal is
directly dropped from the WSD9 to the local OTU. The remaining signals after wavelength
dropping pass through the WSD9 board and travel to the downstream.
The signal flow of the WSM9 reverses that of the WSD9. A single wavelength or a
channel of multiplexed signals to be added from the local client equipment is input through
a wavelength adding interface on the WSM9. In the case of adding multiple wavelengths,
the M40 board multiplexes the multiple wavelengths into one channel of multiplexed
signals and sends it to the WSM9. In the case of adding a single wavelength, this
wavelength is directly added from the local OTU to the WSM9.
P10
Finally, let's study the third networking mode of the ROADM node, in which the
ROADM node uses the WSD9+RMU9 board combination. Compared with the second
networking mode, the WSM9 is replaced with the RMU9 of a lower cost in the third
networking mode. The RMU9 has only the wavelength adding and multiplexing functions
and does not have the wavelength selective grooming function that the WSM9 has. If the
RMU9 accesses multiple wavelengths, the M40 or an optical add/drop multiplexing unit
![Page 35: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/35.jpg)
5
(such as the MR4 or MR2 board) multiplexes the multiple wavelengths into one channel of
multiplexed signals and sends it to a wavelength adding interface on the RMU9. If the
RMU9 accesses a single wavelength, this wavelength directly travels from the local OTU
to a wavelength adding interface on the RMU9.
P11
Now let's turn to part 2 of Chapter 1. Part 2 describes the basic concepts involved in
optical power calculation.
What units can optical power be expressed in? Optical power can be expressed in
mW, dBm, or dB. Generally, dB is used to express optical power attenuation or gain.
How are the units calculated? It's well known that mW is a basic unit to express power.
In fact, dBm is a unit calculated in this way: Suppose that P denotes a power value
expressed in mW. The result of 10 times of the logarithm of the ratio of P to 1 mW is the
power value expressed in dBm. The following is the calculation formula. dB is a unit
calculated in this way: Suppose that P1 and P2 denote two power values expressed in
mW. In this case, P2 is a certain number of mW or dB but not dBm higher or lower than P1.
The next slide explains the reason. The result of 10 times of the logarithm of the ratio of
P2 to P1 is the power value expressed in dB.
Let's try out a quiz. Use the preceding two formulas to calculate the results of the
following five test questions. When –10 dBm substitutes P in the formula, the result is 0.1
mW. Likewise, 0 dBm equals 1 mW; 10 dBm equals 10 mW; and 20 dBm equals 100 mW.
The answer to the last test question is: 20 dBm - 10 dB = 10 dBm. You can comprehend
this answer in this way: Because dB expresses the value of power gain or attenuation, 20
dBm is 10 dB larger than 10 dBm. That is, 20 dBm - 10 dBm = 10 dB. Transpose 10 dBm
and 10 dB in the equation, and the equation changes to 20 dBm - 10 dB = 10 dBm.
P12
Now let's study the formula for calculating total optical power, which is the most
frequently used in the WDM domain. It's well known that the optical power of each
wavelength of a WDM product must be flattened to the same value. Suppose that both the
optical power values P1 and P2 equal the single-wavelength optical power Psingle, then the
total optical power Ptotal equals two times of Psingle. Note that the all these power values are
expressed in mW. If they are expressed in dBm and dB, Ptotal = Psingle + 10lg2. Where,
Psingle is expressed in dBm and 10lg2 is expressed in dB. Likewise, if the number of
wavelengths of a WDM system is N, Ptotal = Psingle (dBm) + 10lgN (dB).
P13
Now let's summarize the basic concepts of and useful tips for optical power
calculation. They help in calculating optical power during deployment and maintenance.
Bear in mind the first tip for optical power calculation: Optical power values expressed
![Page 36: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/36.jpg)
6
in dBm can be subtracted from each other but cannot be added to each other. When the
formula for calculating optical power values P1 and P2 expressed in dBm in the equation
substitutes P1 and P2 for subtraction, the calculated result of the equation can be
expressed in dB. Hence, optical power values expressed in dBm can be subtracted from
each other. When the formula for calculating optical power values P1 and P2 expressed in
dBm in the equation substitutes P1 and P2 for addition, the result of the equation cannot
be calculated. Hence, optical power values expressed in dBm can be added to each other
only after they are converted into values expressed in mW. The equation P(dB) = P1(dBm)
- P2(dBm) shows that the result of one value expressed in dBm minus another value
expressed in dBm is expressed in dB. After P and P2 are transposed, the equation
P2(dBm) = P1(dBm) - P(dB) shows that the result of one value expressed in dBm minus
another value expressed in dB is expressed in dBm.
P14
Bear in mind the second tip for optical power calculation: Remember some optical
power values that are frequently used.
It can be calculated that 10lg2 = 3. Hence, 10lg4 = 2 × 10lg2 = 6. Likewise, 10lg8 = 9,
10lg16 = 12, and 10lg32 = 15. It also can be calculated that 10lg10 = 10. Hence, 10lg20 =
10 + 10lg2 = 13, 10lg40 = 10 + 10lg4 = 16. Remembering these frequently used optical
power values helps you quickly calculate in your head some typical total optical power
values configured for WDM networks.
Let's do another quiz. Suppose that a WDM network is configured with 80 channels,
and the optical power of each channel is flattened to the same value +4 dBm. Calculate
the total optical power. By using the preceding two tips and the formula Ptotal = Psingle +
10lgN (N denotes the number of wavelengths), you can quickly calculate in your head the
total optical power Ptotal = 4+ 10lg80 = 4 + 10 + 10lg8 = 4+ 10 +9 = 23 dBm.
P15
Optical power calculation involves three types of common specifications: insertion
loss (IL), optical amplifier unit parameters, and OTU parameters.
For the common specifications, you can refer to the following documentation:
Approach 1: Refer to section "Technical Specifications" in the Product Description
manual.
Approach 2: Refer to Appendix D "Quickfinder of Board Specifications and
Functions" in the Hardware Description manual.
Approach 3: Refer to section "Board Specifications" in the board description chapter
in the Hardware Description manual.
For the OAU parameters, you can also refer to the Commissioning Guide.
The manuals of WDM products are available on Huawei Support website. You can
obtain them from the following directory:
Documentation → Optical Network Product Line → WDM → OptiX OSN 6800 →
![Page 37: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/37.jpg)
7
Product Manuals
P16
Firstly, let's take a look at the first parameter involved in optical power calculation:
insertion loss (IL).
Definition of IL: The result of the input optical power Pin minus the output optical
power Pout when the optical signals travel over a passive optical component. IL is
expressed in dB. Why must it be a passive optical component? The reason is that to
ensure that the test result indicates the pure IL, the optical signals must not be
regenerated or amplified in the optical component.
P17
Take the MR2 board as an example. The IL between the IN and D1 optical interfaces
of the MR2 board is the same as that between the IN and D2 optical interfaces of the MR2.
The wavelength dropping IL is a maximum of 1.5 dB; the wavelength adding IL between
the A1/A2 and OUT optical interfaces is a maximum of 1.5 dB; and the IL between the MI
and OUT optical interfaces is a maximum of 1.0 dB.
P18
IL of dispersion compensation modules (DCMs) is a special specification of WDM
products, which is usually neglected when we concern about the specifications of various
boards. For the specifications of DCMs, refer to section "Technical Specifications" in the
Product Description manual. The section "Technical Specifications" also provides the
specifications of various boards.
The specifications of DCMs vary with the DCM type. For details, refer to the following
table.
P19
Then, let's take a look at the second type of parameters involved in optical power
calculation: optical amplifier unit parameters.
There are five common optical amplifier unit parameters: input optical power, output
optical power, nominal maximum output optical power, typical input optical power, and
optical amplifier gain.
For the definition of each specification, see the following optical amplifier unit diagram.
Both the input optical power and output optical power refer to the total optical power; both
the nominal maximum output optical power and typical input optical power refer to the
single-wavelength optical power. The total gain of the optical amplifier unit equals the
output optical power minus the input optical power. The single-wavelength gain equals the
single-wavelength output optical power minus the single-wavelength input optical power.
![Page 38: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/38.jpg)
8
In the case of standard system commissioning, the single-wavelength gain equals the
nominal maximum single-wavelength output optical power minus the typical
single-wavelength input optical power. Because of the influence of optical amplifier unit
gain flatness, the total gain and single-wavelength gain might be different.
P20
After you learn the basic information about optical amplifier unit specifications, you
might like to know more details. For more details, you can refer to the Hardware
Description manual. The Hardware Description manual provides the specifications of
optical amplifier boards, such as the input and output optical power ranges and the gain
range. For such specifications, you can also refer to Appendix D "Quickfinder of Board
Specifications and Functions" in the Hardware Description manual. The specifications
vary with the type of the optical amplifier boards.
P21
For the commissioning specifications, namely, nominal maximum single-wavelength
output optical power and typical single-wavelength input optical power, of optical amplifier
units, refer to section "Commissioning the EDFA Optical Power" in the Commissioning
Guide.
The following table lists the typical single-wavelength input optical power values of
various optical amplifier boards used in the OptiX OSN 6800 products.
P22
The following table lists the nominal maximum single-wavelength output optical
power values of various optical amplifier boards used in the OptiX OSN 6800 products.
P23
Finally, let's take a look at the third type of parameters involved in optical power
calculation: OTU parameters.
There are three common OTU parameters: mean launched optical power, receiver
sensitivity, and receiver overload point. The recommended range of received optical
power is the receiver sensitivity plus 3 dBm receiver overload point minus 5 dBm. You
might ask: Why should the overload point be different from the sensitivity? Why must the
overload point minus 5 dBm? We can comprehend it this way: If the received optical
power of a board is close to the sensitivity, services are interrupted because of loss of
signals on the receive side; if the received optical power of the board is close to the
overload point, the services are interrupted and the optical module is damaged. Hence,
the received optical power of a board should be far from the overload point.
The preceding three specifications vary with the type of WDM- and client-side optical
![Page 39: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/39.jpg)
9
modules on the OTU and the transmission distance. For the board specifications of a
WDM product, refer to section "Board Specifications" in the Hardware Description manual
of the product.
P24
Take the LSX board of the OptiX OSN 6800 product as an example. As provided in
the table on the right, the client-side optical module specifications vary with the module
type. In the case of a 10 km optical module with a rate higher than 10G, the maximum
mean launched optical power is –1 dBm; the minimum mean launched optical power is –6
dBm; the receiver sensitivity is –11 dBm; and the overload point is 0.5 dBm.
P25
Take the LSX board of the OptiX OSN 6800 product as an example. As provided in
the table on the right, the WDM-side optical module specifications vary with the module
type. In the case of an NRZ 40-channel optical module with 800 ps/nm dispersion
tolerance, the maximum mean launched optical power is 2 dBm; the minimum mean
launched optical power is –3 dBm; the receiver sensitivity is –16 dBm; and the overload
point is 0 dBm.
P26
This chapter describes the common specifications involved in optical power
calculation: insertion loss (IL), optical amplifier unit parameters, and OTU parameters.
Section "Technical Specifications" in the Product Description manual of each WDM
product describes the board parameters of the product.
P27
Now let's review what we have learned in this chapter. Answer the following two
questions.
Question 1: What are the measurement units for optical power? For the answer to
this question, you can refer to slide 11.
Question 2: If the single-wavelength input optical power is –4 dBm, what is the total input
optical power of a fully loaded 40-channel WDM system? You can use the formula in slide
12 and the example in slide 14 to calculate the answer to this question is 12 dBm.
P28
Now let's study Chapter 2: Optical Power Calculation.
![Page 40: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/40.jpg)
10
P29
Chapter 2 "Optical Power Calculation" is organized into two parts: calculation of
optical supervisory channel (OSC) optical power and calculation of main-path optical
power.
P30
When calculating the OSC optical power, you can refer to the diagram of the OSC
signal flow between two adjacent nodes. The output optical power at the TM optical
interface of the OSC board SC2 ranges from 0 dBm to –4 dBm; that of the OSC board
SC1 ranges from 2 dBm to 4.5 dBm. Considering that the FIU imports 1.5 dB IL, you can
use this formula: Optical power at the receive end of the OSC (the RM optical interface of
the OSC board) = Optical power at the transmit end of the OSC (the TM optical interface
of the OSC board) - Fiber attenuation - 2 × FIU IL. For example, if the line fiber attenuation
between two adjacent nodes is 12 dB, then the budget optical power at RM equals: 2 - 2 ×
1.5 - 12 = –13 dBm. The supervisory signals are terminated and then regenerated at each
node. Hence, the supervisory system optical power is calculated between two adjacent
nodes.
P31
Then, let's study how to calculate the main-path optical power. First of all, let's learn
some basic concepts.
OAU gain range: A gain range that depends on the hardware performance of the
OAU. For the value of the gain range, refer to the Hardware Description manual. For
example, 20–31 dB.
Typical gain of the OAU: The gain capability of the OAU is a range. Hence, during
optical power commissioning, you need to set the gain of the OAU. Under normal network
conditions, the single-wavelength input and output optical power of the OAU can be
adjusted to the nominal values. At this point, the result of the nominal single-wavelength
output optical power minus the nominal single-wavelength input optical power is the
typical gain.
Configurable gain range of the OAU: In actual applications, the configurable gain
range of the OAU does not equal the OAU gain range. The configurable gain range of the
OAU equals the OAU gain range minus the passthrough IL between the TDC and RDC
optical interfaces. This formula applies to the application scenario where a DCM is
connected between the TDC and RDC. For example, if the gain range of an OAU is 20–31
dB and the insertion loss between the TDC and RDC is 5 dB queried on the T2000, then
the configurable gain range of this OAU is 20–26 dB (actually 15–26 dB. Because the gain
value smaller than 20 dB is not configurable on the T2000, the lower limit of the gain range
does not change).
![Page 41: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/41.jpg)
11
P32
Now let's take a look at the procedure to commission and calculate the optical power
of an OAU.
Adjust the VOA to obtain –16 dBm nominal single-wavelength input optical power of
the OAU. Set the gain to the typical gain value 20 dB to obtain +4 dBm nominal maximum
single-wavelength output optical power of the OAU.
If the input optical power fails to be adjusted to the nominal value, set the gain of the
OAU to a proper value obtain the nominal output optical power. In this case, the
configurable gain range of the OAU need be calculated. The configurable gain range of
the OAU equals the OAU gain range minus the passthrough IL between the TDC and
RDC optical interfaces. For example, if the IL between the TDC and RDC is 5 dB (it
approximates the DCM IL plus the fiber connector IL) queried on the T2000 and the gain
range of an OAU is 20–31 dB, then the configurable gain range of this OAU is 20–26 dB.
If the single-wavelength output optical power can reach up to only –20 dBm, after the
configurable gain range is calculated, 24 dB gain is required if the single-wavelength
output optical power is the nominal single-wavelength output optical power plus 4 dBm.
The 24 dB gain is within the configurable gain range 20–26 dB of the OAU. Hence, set the
gain of the OAU to 24 dB.
If the gain value to be set is beyond the configurable gain range, for example, the
single-wavelength input optical power is –24 dBm, set the gain of the OAU to 28 dB obtain
the nominal single-wavelength output optical power. This is a rare case. It indicates that
the client fiber attenuation is much larger than the designed value. In this case, stop the
commissioning and notify the customer to solve the fiber attenuation problem.
Hence, if you set the gain of an OAU to a proper value, the output optical power of
this OAU equals the input optical power plus the gain of the OAU. You can also obtain the
gain of this OAU by querying on the T2000 the performance of the OAU. This document
tells you how to set the gain of the OAU, which helps in actual deployment.
P33
Let's take an example to study how to calculate the main-path optical power.
Suppose that nodes A and B form a point-to-point network. The two nodes are 40 km
away from each other; the fiber attenuation between the two nodes is 12 dB. The board
configuration of node A is the same as that of node B, that is, the OBU101 board is used
on the transmit side and the OAU101 is used on the receive side.
P34
Firstly, let's study the internal signal flow in the transmit direction of node A and the
relevant specifications. Suppose that the specifications of the boards are as follows:
- Typical output optical power of the OTU board: –2 dBm
- Minimum IL of the VOA: 2 dB
- IL of the M40: 6.5 dB
![Page 42: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/42.jpg)
12
- Nominal input/output optical power of the OBU101: –20/0 dBm
- Typical gain of the OBU101: 20 dB
- IL of the FIU: 1.5 dB
P35
Based on the various specifications of boards, we can conclude that the output
optical power of the OTU is –2 dBm. When the optical signals travel over the VOA and
M40, the VOA adjusts the single-wavelength input optical power to the nominal value –20
dBm. The OBU101 provides the optical signals with 20 dB gain, and thus the output
optical power of the OTU reaches the nominal maximum single-wavelength output optical
power 0 dBm. After the optical signals are fed to the fiber line through the FIU, the line
optical power is –1.5 dBm.
P36
The last slide shows how to calculate single-wavelength optical power. Together with
the formula for calculating multiplexed optical power, the multiplexed optical power at the
OUT optical interface of the FIU equals –1.5 + 10lgN (dBm). Where, N denotes the
number of wavelengths.
P37
After the multiplexed signals are fed to the line, considering the line attenuation, the
optical power at the IN optical interface of the FIU at node B equals –13.5 + 10lgN (dBm).
P38
The method of calculating the optical power at node B is similar to that at node A.
First of all, query the specifications of each board.
- IL of the FIU: 1.5 dB
- Minimum IL of the VOA: 2 dB
- Nominal single-wavelength input/output optical power of the OAU1: –16/4 dBm
- Typical gain of the OAU1: 20 dB
- IL of the D40: 6.5 dB
- Typical received optical power of the OTU: –16 dBm (APD) or –9 dBm (PIN)
P39
Use the preceding specification values to substitute the corresponding parameters in
the signal flow. The input optical power at the IN optical interface of the FIU equals –13.5
+ 10lgN (dBm). Because the IL of the FIU is 1.5 dB, the output optical power at the TC
optical interface of the FIU equals –15 + 10lgN (dBm) after the optical signals travel over
![Page 43: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/43.jpg)
13
the FIU. Where, –15 dBm is the single-wavelength output optical power. Because the
inherent IL of the VOA is 2 dB, the input optical power of the OAU101 equals –17 + 10lgN
(dBm) after the optical signals travel over the VOA. Where, –17 dBm is the
single-wavelength input optical power, which is lower than the nominal single-wavelength
input optical power of the OAU101. Hence, based on the preceding method, you need to
set the gain of the OAU101 to 21 dB to ensure that the output optical power of the
OAU101 reaches the nominal gain which is +4 + 10lgN (dBm). After the optical signals
travel over the D40:
Single-wavelength optical power = Total optical power - 10lgN - D40 IL
Hence, the output optical power at any DM optical interface of the D40 is –2.5 dBm. To
ensure that the received optical power of the OTU is around the typical value, add a fixed
optical attenuator to the receive-side optical interface of the OTU. In the case of the PIN,
add a 7 dB fixed optical attenuator; in the case of the APD, add a 15 dB fixed optical
attenuator.
P40
Now let's take the OTM-OLA-OTM networking mode as an example to study how to
calculate the optical power at an OLA node. In the transmit direction of nodes A and C, the
OBU103 board is used. Hence, the nominal launched optical power of the OBU103 equals
+4 + 10lgN (dBm). Node A is 50 km away from node B, and the fiber attenuation between
nodes A and B is 15 dB. Hence, the received optical power, which is sent from node A, at
the IN optical interface of the west FIU at node B equals –11 + 10lgN (dBm). Node B is 80
km away from node C, and the fiber attenuation between nodes B and C is 24 dB. Hence,
the received optical power, which is sent from node C, at the IN optical interface of the
east FIU at node B equals –20 + 10lgN (dBm). Node B is an OLA, which uses the
OAU101 and type-B DCM.
P41
Optical power calculation of optical signals from west to east:
First of all, query the IL and optical power specifications of each board at node B.
- Nominal single-wavelength input/output optical power of the OAU1: –16/+4 dBm
- Gain range of the OAU1: 20–31 dB
- IL of Type-B DCM: 5 dB
- IL of the FIU: 1.5 dBThen, calculate the optical power at each reference point. The
received optical power at the IN optical interface of the west FIU equals –11 + 10lgN (dBm)
and equals –12.5 + 10lgN (dBm) after the optical signals travel over the FIU. After being
adjusted by the VOA, the input optical power of the OAU101 equals the nominal value –16
+ 10lgN (dBm). The gain range of the OAU101 is 20–31 dB. Considering the IL of the
DCM, the gain range of the OAU101 is 20–26 dB. Because the nominal output optical
power of the OAU101 is +4 + 10lgN (dBm), the gain need be set to 20 dB.
To calculate the optical power of optical signals in one direction of the OLA node to is
![Page 44: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/44.jpg)
14
mainly to calculate the typical single-wavelength optical power of the optical amplifier
board. To debug board embedded software is to adjust the VOA before the optical
amplifier to make the optical power at each reference node reach the nominal value. The
optical power calculation of optical signals in the other direction of the OLA node is similar
to that in the preceding direction.
P42
Now let's do another practice on optical power calculation. Answer the following three
questions:
Question 1: Should a VOA be added before the OAU101?
Question 2: What is the desired gain to be set for the OAU101?
Question 3: What is the actual gain of the OAU101?
Answer to question 1: With the IL of the FIU considered, the single-wavelength output
optical power at the TC optical interface of the FIU is 21.5 dBm which is far lower than –16
dBm required. Besides, the VOA has 2 dB inherent IL. In the case of a mechanical VOA, it
must be removed on site. In the case of an electrical VOA (EVOA) board on site, it should
be retained for remote maintenance.
Answer to question 2: With the IL of type-B DCM considered, the configurable gain
range of the OAU101 is 20–26 dB. When the gain is set to 25.5 dB, the output optical
power of the OAU101 reaches the nominal value.
Answer to question 3: The actual gain of the OAU101 equals the configured gain plus
the IL of the DCM, which is 30.5 dB.
P43
Now let's take a look at how to calculate the optical power at an FOADM node.
The following figure shows the networking diagram. In the transmit direction of nodes
A and C, the OBU103 is used. The output optical power of the OBU103 is +4 + 10lgN
(dBm). At node B, the OAU101 or OBU103 and the type-B DCM is used. In addition, two
MR2 boards are used at node B to add and drop wavelengths. Node A is 50 km away from
node B, and the fiber attenuation between nodes A and B is 15 dB. Hence, the input
optical power at the IN optical interface of the west FIU at node B equals –11 + 10lgN
(dBm).
P44
Now let's take a look at the internal signal flow from east to west of node B and the
optical power.
First of all, query the specifications of each board at node B.
- Nominal single-wavelength input/output optical power of the OAU101: –16/+4 dBm
- Gain range of the OAU101: 20–31 dB
- IL of Type-B DCM: 5 dB
![Page 45: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/45.jpg)
15
- IL of the FIU: 1.5 dB
- IL between the IN and DM optical interfaces of the MR2: 1.5 dB
- IL between the IN and MO optical interfaces: 1 dB
- IL between the OUT and MI optical interfaces: 1 dB
- Nominal single-wavelength input/output optical power: –19/4 dBmThe input optical
power at the IN optical interface of the FIU equals –11 + 10lgN (dBm).
P45
Now let's calculate the optical power at each reference node. Based on the preceding
experience, it is easy to know that the optical power at the OUT optical interface of the
OAU101 equals +4 + 10lgN (dBm). The output optical power at the D01/D02 optical
interface of the MR2 is +2.5 dBm. Suppose that all OTUs at the receive end use the PIN,
add a 10 dB fixed optical attenuator to each OTU.
Then, let's calculate the single-wavelength optical power of passthrough wavelengths.
The single-wavelength optical power of passthrough wavelengths at the OUT optical
interface on the OAU101 is +4 dBm. Considering the optical power of passthrough
wavelengths of the two MR2 boards and 2 dB minimum attenuation of the VOA, the
single-wavelength optical power at the IN optical interface of the OBU103 should be a
minimum of 0 dBm. To make the single-wavelength optical power of the OBU103 reach
the nominal value, adjust the VOA between the two MR2s. That is, adjust the passthrough
wavelengths to make the single-wavelength optical power of the OBU103 reach the
nominal value. In the case of wavelength adding through the east-transmit OTU, adjust
the VOA at the wavelength adding channel to make the single-wavelength optical power
of the OTU reach the nominal value. In this way, the input optical power of the OBU103 is
–19 + 10lgN (dBm). The output optical power at the OUT optical interface of the east FIU
equals 2.5 + 10lgN (dBm).
The optical power calculation of optical signals in the other direction of the OLA node
is similar to that in the preceding direction.
P46
Finally, let's take a look at how to calculate the optical power at an ROADM node.
Again, a network formed by nodes A and B is considered as an example. The optical
amplifier board configuration of the two nodes in this example is the same as that in the
previous example. Node B uses two ROAM boards to add and drop wavelengths.
P47
The following figure shows the internal signal flow of ROADM node B. Likewise, refer
to the Hardware Description manual to query the IL and gain specifications of each board.
Note that the IL between each two optical interfaces of the ROAM board vary.
![Page 46: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/46.jpg)
16
P48
The optical power calculation method of the optical amplifier board in this example is
the same as that in the previous example. The output optical power of the OAU101 equals
+4 + 10lgN (dBm). After the optical signals travel over the ROAM board, because the IL
between the IN and DM optical interfaces of the ROAM board is 7 dB, the output optical
power at DM equals –3 + 10lgM. Where, M denotes the number of the wavelengths
dropped through DM. Because the passthrough IL between the IN and EXPO optical
interfaces is 3 dB, the output optical power at EXPO on the west ROAM board equals +1 +
10lgN (dBm). After the wavelengths pass through the east ROAM board, the
single-wavelength optical power is –2 dBm. Adjust the internal VOA of the ROAM board to
make the single-wavelength output optical power of the OBU103 reach the nominal value
–19 dBm. Hence, the total input optical power of the OBU103 equals –19 + 10lgN (dBm);
the output optical power at the OUT optical interface on the east FIU equals +2.5 + 10lgN
(dBm).
The optical power calculation of optical signals in the other direction of the OLA node
is similar to that in the preceding direction.
P49
Now let's take a look at how to calculate the optical power at ROADM node B that
uses the WSD9+RMU9 board combination for wavelength adding/dropping. ROADM
node B that uses the ROAM board differs with ROADM node B that uses the
WSD9+RMU9 board combination in only that the IL of the WSD9+RMU9 boards is
different from the IL of the ROAM board. You can deduce the other cases by analogy.
P50
The optical power calculation of the signal flow shown in this slide is the same as that
in the case of ROADM node B that uses the ROAM board. Because the IL of the WSD9 is
different from the IL of the ROAM board, the optical power of passthrough wavelengths
equals –4 + 10lgN' (dBm). Where, N' denotes the number of passthrough wavelengths. In
this example, because of sufficient optical power budget, the optical power of each
wavelength of the OBU103 can be adjusted to the nominal value –19 dBm. If the optical
power budget id insufficient, add an optical amplifier board between the TOA and ROA
optical interfaces of the RMU9.
P51
Finally, let's take a look at how to calculate the optical power in the third ROADM
configuration scenario in which the WSD9+WSM9 board combination is configured. The
calculation method in this scenario is the same as that in the previous two scenarios,
which is omitted in this slide.
![Page 47: 8-Optical Power Calculation Training](https://reader034.vdocuments.site/reader034/viewer/2022042500/55cf98ff550346d0339af15a/html5/thumbnails/47.jpg)
17
P52
You can calculate by yourself the optical power at each reference node in this
scenario.
P53
After studying this chapter, you should master the following knowledge:
Calculation of OSC optical power
Calculation of optical power of the OTM
Calculation of optical power of the OLA
Calculation of optical power of the FOADM
Calculation of optical power of the ROADM (ROAM)
Calculation of optical power of the ROADM (WSD9+RMU9)
Calculation of optical power of the ROADM (WSD9+WSM9)
The methods of calculating optical power in the preceding networking modes cover
all networking scenarios for WDM products. Mastering these methods greatly helps in
deployment and maintenance of WDM products.
P54
Thank You!