IEEE802.3aq Channel model ad hocTask 2: Time-varying study & modal noise

Meeting notes, 15 July 2004Jonathan King

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, Rsoft• Yu Lung Chau, IKRI• Matt Traverso, Opnext• 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• Lars Thon, Aeluros• Petar Popeljugoski contributions from• Yu Sun, Optium• Peter Hallemeier, Optium

Objectives of meeting

• define goals and tasks • agree time line

– September input required by task 1

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 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

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

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

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

• Aronson_1_05_04 – Proposals for measurement of channel time variance

Next meeting

• Wednesday morning 9am PCT, 5pm UK