Optical Performance Monitoring Method Based On A Pair Of Low-bandwidth Coherent Receivers

As for the cost of the monitoring system and the compatibility in the field of optical performance monitoring,this paper proposes an optical performance monitoring system based on a pair of low-bandwidth coherent receivers.Different from the traditional way of full bandwidth detection directly,with application of digital signal processing algorithm,the lowbandwidth coherent detection can realize high performance and cost-effective optical performance monitoring method for its characteristics of low cost and multidimensional receiving.It mainly monitors the objects which are common to the fiber and have severe influence on the optical signal after the long-distance optical transmission link,including Chromatic Dispersion(CD),Polarization Mode Dispersion(PMD)and Amplifier Spontaneous Emission Noise(ASE)parameter.In the scheme,building a pair of low-bandwidth coherent receivers system and obtaining the special optical signal information by frequency beating.According to the receiver data,designing the program of cross-correlation in time domain,stokes rotation vector recovery in frequency domain and signal-to-noise ratio algorithm to monitor the parameters of long-distance optical transmission network nodes.The CD estimation range is theoretically infinite.The PMD estimation range is limited to the maximum of 1/2 symbol period and Optical Signal to Noise Ratio(OSNR)is tested from 10 dB to 20 dB.Simulation results show that for a 28 GHz baud Quadrature Amplitude Modulation(QAM)transmission system,with dual 1 GHz coherent receivers,the monitoring error for CD,PMD and OSNR is 30 ps/nm,0.5 ps and 1 dB,respectively.We also experimentally verified it for a 12GBit/s NRZ transmission system with dual 1 GHz coherent receivers.The monitoring error for CD and PMD is 60 ps/nm and 1.5 ps,respectively.The optical performance monitoring method based on a pair of low-bandwidth coherent receivers has a very high monitoring precision,can achieve the same effect as the full bandwidth receiving system.It also has compatibility,can monitor multiple parameters under the same system at the same time.As for the request of simplicity,low cost and high performance in the new generation optical network performance monitoring technology,the optical monitoring method based on a pair of low-bandwidth coherent receivers is a meaningful and applied to actual innovative solutions.