HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Slow-Light Photonic Crystal Waveguides

Key Enabler For Future Optical Network Technologies

Panagiotis Kanakis, UOAThomas Kamalakis, HUA

Adonis Bogris, TEI of Athens

18th Panhellenic Conference on Informatics 2-4 October 2014

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Outline• Problems and limitations of electronics in

optical network nodes.

• Optical Transparency : PCW.

• PCW applications.

• Designing slow-light PCW.

• Conclusions.

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Problems and limitationsElectro-

optic bottleneck

ComplexityPower

Consumption

Cost Footprint

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Future Problems and Limitations

• Heat dissipation.

• Future estimation.

0 1

• Quantum information (qubit)!!!

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Optical Transparency

• Data format independence.

• Opportunity to increase data rate beyond the capabilities of electronics.

• Reduction of total power consumption (due to none or less electro-optic conversions).

• Less need for heat dissipation techniques (i.e. increase of compactness).

• Qubit friendly.

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Photonic Crystal Slab1-D

2-D

3-D

er : Dielectric constant of the RED material.eb : Dielectric constant of the BLUE material.

3-D Slab Waveguide

Bulk Crystal

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Department of Informatics and Telematics

Photonic Crystal Waveguide

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Department of Informatics and Telematics

Photonic Crystal Waveguide (PCW)

0.35 0.4 0.45 0.50.26

0.265

0.27

0.275

k/2

/

2c

0.3 0.35 0.4 0.45 0.50.255

0.26

0.265

0.27

k/2

/

2 cLow Group Velocity Dispersion (GVD), β2

Standard W1 waveguide

Dispersion Engineered

How does this help in optical transparency ?

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Photonic Crystal Waveguide (PCW)

Wavelength Conversion

PCWStorage Capacity

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Storage Capabilities of PCWs

0gDBP n

max 1

W g

b

L vN

R

Delay BW Product (DBP) Maximum Storage Capacity

Which is the best design?

Considered design parameters

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Step by Step Optimization Process

Sequence of steps:1st Step 2nd Step 5th Step

Design Parameters:

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Νmax : 1st Step (Rb=40Gb/s)

0.35 0.4 0.45 0.50

10

20

30

40

50

k/2

n g

0.35 0.4 0.450

5

10

15

20

25

k/2

Nm

ax

Standard W1

1st Step

0.35 0.4 0.45 0.50.258

0.26

0.262

0.264

0.266

0.268

0.27

k/2

/

2c

Band Diagram

Group Index

Storage Capacity

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Νmax : 2nd Step (Rb=40Gb/s)

Storage Capacity

0.35 0.4 0.450

5

10

15

20

25

k/2

Nm

ax

Standard W1

1st Step

2nd Step

0.3 0.35 0.4 0.45 0.50.25

0.255

0.26

0.265

0.27

k/2

/

2c

Band Diagram

0.3 0.35 0.4 0.45 0.50

10

20

30

40

50

k/2

n g

Group Index

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

0.35 0.4 0.450

5

10

15

20

25

30

k/2

Nm

ax

Standard W1

1st Step

2nd Step

4th Step

0.35 0.4 0.45 0.5

0.258

0.26

0.262

0.264

0.266

0.268

k/2

/

2c

Νmax : 4th Step (Rb=40Gb/s)Band Diagram

Design Specifications

y1/a y2/a y3/a r1/a Nmax ng

4th Step

0.1297 -0.0248 0.399 0.25 31.2 24

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Νmax : 4th Step (Rb=100Gb/s)

0.3 0.35 0.4 0.45 0.50

10

20

30

40

50

60

70

k/2

Nm

ax

Standard W1

4th Step

Design Specifications

y1/a y2/a y3/a r1/a Nmax ng

4th Step

0.1394 0.0246 0.0181 0.2645 65 20.4

0.3 0.35 0.4 0.45 0.50.255

0.26

0.265

0.27

0.275

k/2

/

2c

Band Diagram

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

All-Optical RAM

• Array of PCW bit memory.

• Total buffering holding time: 168nsec.

• Energy and power consumption 24fJ/bit

and 10μW respectively.

OFC/NFOEC, vol. 1, no. 3, pp. 6-10 March 2011

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Department of Informatics and Telematics

Wavelength Conversion : FWM

( )

(0)i

s

P L

P

Conversion Efficiency

Efficiency-BW-Tunability (EBT)

EBT

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Department of Informatics and Telematics

Step-by-step Optimization Process

Δy1 Δy2 Δy3 r1 r2 r3ΕΒΤ(n

m2)

Βήμα 1ο 0.083 0 0 * * * 1.6

Βήμα 2ο 0.144 0.09

8 0 * * * 2.5

Βήμα 3ο 0.15 0.10

8 0.109 * * * 3.6

Βήμα 4ο 0.147 0.10

8 0.108 0.23 * * 5.2

Βήμα 5ο 0.146 0.09

8 0.013 0.229 0.23 * 6.5

Βήμα 6ο 0.145 0.10

4 0.056 0.2301

0.2305

0.2405 7.7* Unchanged

parameter.

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Optimum PCW design

ηmax -27dB

Δλ 61nm

δλ 58nm

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Summing Up

• We have presented a new design optimization method able to include multiple structural parameters.

• New figure of merits (Nmax and EBT) include real aspects (like propagation loss, dispersion and Bandwidth capabilities) to the estimation of more realistic designs.

• Generally it is still early for PCW optical memories.• Low capacities is currently the major drawback.• However in the future optical memories will not be an

alternative but a necessity due to quantum information.

Our opinion

This research has been funded under the framework of the “Archimedes III: Funding of Research Groups in TEI of Athens”

project of the “Education & Lifelong Learning Operational Programme.”

HAROKOPIO UNIVERSITY OF ATHENS - HUA

Department of Informatics and Telematics

Thank you.