Abstract: 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.

Abstract: 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.

Abstract: Embodiments of the present invention relate to an optical signal processing system and method that uses, for example, four-wave mixing to produce a wavelength converted optical data-bearing signal having a power level that is proportional to at least the square of the power level of an optical data-bearing signal.

Abstract: 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.

Abstract: Methods and apparatus for creating a Bragg grating in an optical waveguide having an optical fiber on which the Bragg grating is defined, the Bragg grating having an actual response which closely approximates a desired response. The Bragg grating comprises a plurality of lines, each line being defined by a respective strength, and each line having a relative displacement from adjacent lines. The Bragg grating is designed using a serial iterative response. The serial iterative process can be used to calculate the strength and the line spacing of at least some of the lines. The serial iterative process can further be a function of a coupling function, which is a function of the strength and line spacing of the lines of the grating. A moving window can be used to limit the number of reflections in the impulse response which is used to calculate the next serial line spacing.