Optical Performance Monitoring For Next Generation Reconfigurable Optical Network Based On Asynchronous Amplitude Histogram

As early as in2000, optical performance monitoring (OPM) as a role of in line opticalchannel monitoring, central wavelength monitoring and optical signal to noise (OSNR)monitoring is widely concerned by related industry, with the spring up of optical industry.Corresponding products are produced as well, however, which can’t be widely applied to actualsystem. Not until2008, with technique of reconfigurable optical add/drop multiplexer (ROADM)becoming mature, intelligent optical network growing up and third Generation networkpromotion, OPM shake off its dispensable character and is developing into a function module ofnecessary in the optical communication network in order to maintain high quality and robust ofthe optics communication.In this paper, researches on OPM techniques in reconfigurable optical network cover asfollows:The first, according to the different realization fields, great diversity of OPM techniques arediscussed and sorted as two categories of optical field and electronic field in the paper. In opticalfield, optical impairments include OSNR, chromatic dispersion (CD), polarization modedispersion (PMD) etc., therefore, the OPM techniques are presented in accordance with thevariety of optical impairments. In electronic field, the corresponding OPM techniques are alsoproposed based on parameters, such as Q-factor, bit error rate (BER), eye diagram, amplitudehistogram.The second, considering various of characteristics of low costs, bit rate transparency, simplerealizations, the OPM technique based on asynchronous amplitude histogram (AAH) can beapplied to higher order quadrature amplitude modulation (QAM) signals.The last, systems of25Gsym/s16/64-QAM are set up by OptiSystem, a sort of simulationsoftware, including the modulation, transmission, demodulation and post processing. In the givenQAM systems, OSNR and CD monitoring for higher order QAM based on AAH are presented.Simulation results show that the presented monitoring technique with high monitoring sensitivity,moreover, can also be applied to much higher order QAM formats such as128-QAM.Without demodulating the received signals, the OPM technique proposed in this paperbased on AAH can detect the quality of signals. The received signal is sampledasynchronously,thus clock information and high-speed sampling units are unnecessary, resulting in low cost and highly reliable, therefore, the OPM techniques can be applied to monitoring theresidual chromatic dispersion of a transmission link in the next-generation optical networks.