9/17/04ieee 802.3aq ad-hoc task 4 comparison of some cambridge model results with simulation results...

9/17/04 IEEE 802.3aq Ad-hoc task 4

Comparison of some Cambridge model results with simulation

results of RSoft and Optium in-house simulators

Gary Shaulov, RSoft Design GroupYu Sun, Optium

9/17/04

Outline

• The purpose of these preliminary studies was to check the results of Cambridge model for scaled/non-scaled index profiles against results by other mode solvers (both commercial and proprietary);

• Just two fiber models were studies – fibers #23 and #29 – before and after scaling;

• Optium in-house simulator results were compared with RSoft commercial multimode simulator (ModeSYS™ ) results

• Optium and RSoft simulation results were compared with results from Cambridge model for output pulse shapes, DMD evolution, scaling factors, and OFL bandwidth.

9/17/04

Parameters:1. Input beam: Gaussian with 7 μm FWHM2. Input pulse: Gaussian with 50 ps FWHM3. Wavelength: 1300 nm4. Fiber interested: Cambridge #23 and #295. Offset considered: 17, 20 and 23 μm 6. Fiber length: 300m

Comparison of RSoft and Optium in-house simulators

Pulse shape of output from multimode fibers were studied for new scaled Cambridge index profiles

9/17/04

Comparison of Rsoft and Optium in house simulator

Fiber #23 with offset of 17 μm

OptiumRSoft

9/17/04



OptiumRSoft

9/17/04



RSoftOptium

9/17/04

Fiber # 29, offset 17 μm Fiber # 23, offset 17 μm

Comparison of pulse shapes: Optium vs Rsoft

Very good agreement for both fibers

Blue curves: OptiumRed curves: RSoft

9/17/04

Blue curves: OptiumRed curves: Cambridge

Fiber #23Offset 17 μm

Fiber #29Offset 17 μm

Comparison of pulse shapes: Optium vs Cambridge

Good agreement for fiber #29 but not so good for fiber #23

9/17/04

DMD study for scaled and non-scaled index profiles – comparison of Rsoft and Cambridge

results

• Two fiber index profiles were studied - fiber 23 and 29 (according latest to Cambridge release) – first non-scaled and

then scaled profiles.

9/17/04

Fiber # 23

• Note: fiber #23 in previous Cambridge release for 65 fibers is fiber #18

9/17/04

Fiber # 23 – cont’d

• Cambridge model gives scaling factor for fiber #23 f=2.7054 (r.3.0)

• According to J.Abbott’s presentation OFL_BW=600 MHz km, DMD mean =1.98 ns/km

• RSoft simulations give in case of non-scaled index DMD=3.3 ps/m, in case of scaled even higher DMD = 5.9 ps/m.

• The difference in results may be due also to the difference in calculation methods for DMM

Calculated scaling factor = 2/3.3=0.6

Calculated OFL_BW =480 MHz km

9/17/04

Fiber # 29

• Note: fiber #29 in previous Cambridge release for 65 fiber is fiber #24

9/17/04

Fiber # 29 – cont’d

• Cambridge model gives scaling factor for fiber #29 f=0.8424 (r.3.0)

• According to J.Abbott’s presentation OFL_BW=660 MHz km, DMD mean=2.18 ns/km

• RSoft simulations give in case of non-scaled index DMD=5.2 ps/m, in case of scaled index DMD = 4.7 ps/m.

• The difference in results may be due also to the difference in calculation methods for DMD

Calculated scaling factor f=2/5.2=0.38

Calculated OFL_BW =480 MHz km

9/17/04 * See John Abbott’s presentation at telecon 7/28/2004

Corning/Cambridge (DMD scaled) *

RSoft (non-scaled)

DMD results comparison

9/17/04

Preliminary Conclusions

• The agreement between RSoft and Optium in-house simulators is excellent.

• Both RSoft and Optium results are in good agreement with Cambridge results for fiber #29, however for fiber #23 there is discrepancies between Cambridge and RSoft/Optium

• The agreement between RSoft and Cambridge models results in DMD evolution behavior is good except points at very high values of offsets

• More studies needed to identify if the difference comes from difference in approaches to calculate mean DMD

• Cambridge model prescribes to ignore degenerate mode groups with g>20 (or g>18?). It may be not always the case for RSoft and Optium mode solvers – can that be the cause of discrepancies, and should we worry about higher order modes?

9/17/04ieee 802.3aq ad-hoc task 4 comparison of some cambridge model results with simulation results...

Documents