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Time-Varying Effects on LRM Specification: Study and Modal Noise Assessment

This meeting focused on studying time-varying effects for the LRM draft spec, modal noise evaluation, and tracking perturbations. Attendees discussed modal noise penalties for different laser types and mechanisms causing time variance in links. Tasks included placeholder mechanical vibration rates and modeling delay vs. modes for perturbed links. Modal noise spectrum measurements and real-life product expectations were key areas of focus. Previous explorations on modal noise and fiber laser links were reflected upon, paving the way for future discussions. Next meeting set for Wednesday morning.

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Time-Varying Effects on LRM Specification: Study and Modal Noise Assessment

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  1. IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise Meeting notes, 15 July 2004 Jonathan King IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  2. Attendees • Jonathan King, Big Bear Networks • Tricia Hill, Big Bear Networks • John Jaeger, Big Bear Networks • Abhijit Phanse, Scintera • David Cunningham, Agilent • Piers Dawe, Agilent • Gary Schaulov, Agilent • Yu Lung Chau, IKRI • Matt Treverso • Andre van Schyndel, Bookham • Petre Popescu, Quake • John Dallesasse, Emcore • John Ewen, JDSU • Yi Sun, OFS • Nick Weiner, Phyworks • Brian Taylor, Oepic • Paul Kolesar, Systimax • Kevin Witt, Vitesse contributions from • Yu Sun, Optium • Peter Hallemeier, Optium IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  3. Objectives of meeting • define goals and tasks • agree time line • September input required by task 1 IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  4. Goals for task 2 • Study the impact of time varying effects on the LRM draft spec • Provide input to the time varying component of the receiver compliance test • Set a frequency below which EDC is should track (TP3 test rate) • define tracking 'mask' - magnitude of perturbation vs frequency of perturbation • Measure spectrum of time variation effects • what is the product expected to cope with in real life ? what's already out there ? • consensus that measuring this for statistically significant numbers installed links would be an extremely difficult task; • Modeling of extent of time variance of links • e/g. delay vs mode sets for quasi-continuous perturbed link for listed mechanisms • generate impulse responses for quasi-continuously perturbed link for selected launches, over Cambridge fibre set (tbc) and a 'standard link' • Study modal noise of the MMF channel and ensure modal noise is properly accounted for in the LRM draft spec • Assess modal noise penalty for different laser types IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  5. Time variation mechanisms In approx order of significance of magnitude • connector offset • static offset: 3.5 average, 1.8 standard deviation for 50 micron fibre ; check if we need to scale for 62.5 micron fibre. (95% less than 7um) • temporal variability tbd • fibre perturbation • import fibre shaker for measurements • mechanical and polarization • laser wavelength • can be modeled with mode solver • temperature • very slow, believed trackable, not main focus of study Rate tbd • Faster than EQ adaption - noise • modal noise variance can be estimated using previous work • Slower than adaption rate - trackable IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  6. Tasks • Mechanisms: determine a placeholder value for mechanical vibration rate for connectors - John Dallesasse • Experiment: relationship of perturbation spectrum to modal noise spectrum - Abhijit Phanse will check capability for measurements at scintera • Modelling of delay vs modes for quasi continuous perturbed link for listed mechanisms - Yu Sun/Pete Hallemeier • generate quasi continuous impulse responses for perturbed link for selected launches (over Cambridge fibre set) , 'standard link' • Modal noise penalty for different laser types - David Cunningham • Effect of link temperature - Petre Popescu • Real environments - volunteers tbd • Measurements of spectrum of time variation effects • Input on what is the product expected to cope with in real life? • what's already out there describing in building environments IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  7. Previous work • Modal Noise Test Methodology group • 'Measurement of the optical power penalty due to modal noise in multimode fiber laser based links' • Fibre shaker TIA/EIA-455-203 • Sun_1_0704 • Modelled CL and OSL launch sensitivity to connector offset 10+280+10 link IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

  8. Next meeting • Wednesday morning 9am PCT, 5pm UK IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

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