Coherent optical communication

Optical coherent receivers with subsequent DSP show great promise as enabling technologies for ultra-high information rate optical transmission systems. DSP alleviates the need to lock the phases of the LO and transmitter signal, which is one of the limiting factors for the use of coherent receivers in the optical domain. Various optical impairment issues can be addressed in the digital domain, in particular, nonlinearity compensation. One of the major issues still to be addressed for successful implementation of this technology is optimization of the algorithms and implementation methods used for DSP demodulation. Current DSP speeds are not high enough to process high-speed optical signals (e.g. 10 baud). Therefore, parallelization and pipelining techniques must be considered. Moreover, rigorous theoretical analysis of the performance of such receivers is being researched so the various parameters pertaining to the algorithms employed may be optimized.