Comparison of some Cambridge model results with simulation results of RSoft and Optium in-house simulators Gary Shaulov, RSoft Design Group Yu Sun, Optium 9/17/04 IEEE 802. 3 aq Ad-hoc task 4
Outline • The purpose of these preliminary studies was to check the results of Cambridge model for scaled/nonscaled 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 (Mode. SYS™ ) 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
Comparison of RSoft and Optium in-house simulators Pulse shape of output from multimode fibers were studied for new scaled Cambridge index profiles Parameters: 1. Input beam: Gaussian with 7 μm FWHM 2. Input pulse: Gaussian with 50 ps FWHM 3. Wavelength: 1300 nm 4. Fiber interested: Cambridge #23 and #29 5. Offset considered: 17, 20 and 23 μm 6. Fiber length: 300 m 9/17/04
Comparison of Rsoft and Optium in house simulator Fiber #23 with offset of 17 μm Optium 9/17/04 RSoft
Comparison of Rsoft and Optium in house simulator Fiber #23 with offset of 23 μm Optium 9/17/04 RSoft
Comparison of Rsoft and Optium in house simulator Fiber #23 with offset of 20 μm RSoft Optium 9/17/04
Comparison of Rsoft and Optium in house simulator Fiber #29 with offset of 17 μm Optium 9/17/04 RSoft
Comparison of Rsoft and Optium in house simulator Fiber #29 with offset of 20 μm Optium 9/17/04 RSoft
Comparison of Rsoft and Optium in house simulator Fiber #29 with offset of 23 μm Optium 9/17/04 RSoft
Comparison of pulse shapes: Optium vs Rsoft Blue curves: Optium Red curves: RSoft Fiber # 29, offset 17 μm Fiber # 23, offset 17 μm Very good agreement for both fibers 9/17/04
Comparison of pulse shapes: Optium vs Cambridge Blue curves: Optium Red curves: Cambridge Fiber #29 Offset 17 μm Fiber #23 Offset 17 μm 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 • • • Calculated scaling factor = 2/3. 3=0. 6 Calculated OFL_BW =480 MHz km 9/17/04 • Cambridge model gives scaling factor 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
Fiber # 29 • Note: fiber #29 in previous Cambridge release for 65 fiber is fiber #24 9/17/04
Fiber # 29 – cont’d Calculated scaling factor f=2/5. 2=0. 38 Calculated OFL_BW =480 MHz km 9/17/04 • Cambridge model gives scaling factor 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
DMD results comparison RSoft (non-scaled) Corning/Cambridge (DMD scaled) * * See John Abbott’s presentation at telecon 7/28/2004 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? 9/17/04
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