9/17/04ieee 802.3aq ad-hoc task 4 comparison of some cambridge model results with simulation results...
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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
Comparison of Rsoft and Optium in house simulator
Fiber #23 with offset of 23 μm
OptiumRSoft
9/17/04
Comparison of Rsoft and Optium in house simulator
Fiber #23 with offset of 20 μm
OptiumRSoft
9/17/04
Comparison of Rsoft and Optium in house simulator
Fiber #29 with offset of 17 μm
OptiumRSoft
9/17/04
Comparison of Rsoft and Optium in house simulator
Fiber #29 with offset of 20 μm
OptiumRSoft
9/17/04
Comparison of Rsoft and Optium in house simulator
Fiber #29 with offset of 23 μm
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?
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