Nortel Networks Corporation

Ricardo Feced

Robin Paul Rickard

Sotiris Emil Kanellopoulos

Bruce R Napier

Epworth Richard

An optical receiver demodulates optical orthogonal frequency division multiplexed signals and generates a number of subcarrier reference signals, each for demodulating a frequency channel of the frequency division multiplexed signals. It compensates for degradations in the generated reference signals by averaging a number of estimates derived from different inputs to make the references more resilient to degradations. It can encompass time averaging to compensate for amplification noise, and frequency averaging of phase drift estimation to compensate for phase drift caused by reduced source coherence. It can enable longer system reach and/or increased optical power margins by means of better system resilience to amplification noise and reduced source coherence. The bit error rate can be reduced, and/or the capacity can be increased by increasing bit rate or introducing more frequency channels.

Reference phase and amplitude estimation for coherent optical receiver

A method of writing a diffraction grating into a photosensitive optical transmission medium is disclosed, in which a first phase mask is used to generate an interference pattern in a second phase mask substrate and using photolithographic techniques. This produces a second phase mask, which is then use to write a diffraction grating into a photosensitive optical transmission medium. This method enables the line placement in a phase mask to be improved by averaging out the line placement errors.

Growing community of inventors

Sawbridgeworth, United Kingdom

Ricardo Feced