Research On Hyperspectral Efficiency Modulation In Coherent Optical Communication System

With the Internet industry develop rapidly,it is necessary to satisfy user's demand of wide bandwidth due to Network traffic increased dramatically in recent years.To increase the the capacity and spectrum efficiency,researchers gripped the attention to the technology of optical fiber communication.Coherent optical communication technology,which based on high order high dimensional modulation and digital signal processing(DSP)technology with the advantage of new modulation formats to increase spectrum efficiency,long distance relay,and compensation for damage to the circuit in the electric field,become the development direction of the next generation optical fiber communication.This paper focuses on the key technologies in coherent optical communication system,the high order modulation technique in high-speed coherent optical communication system is theoretically analyzed and demonstrated.The main works in this paper are as follows:1.Analyzed the key technologies of high-speed coherent optical communication,include the new modulation formats,narrow line width laser source,transmission link,coherent detection technology and digital signal processing technology.2.Analyzed the hyperspectral efficiency modulations,include the amplitude modulation,the phase modulation and quadrature amplitude modulation.I research the QPSK,8PSK and 16 QAM.It compares them from many aspects such as principles and modulation structures.After analysis,we get the 16 QAM is bast for future transmission system.3.An improved four-level signal generation scheme is proposed.I simulate the DP-16 QAM.Through simulation and analysis,when the angle of polarization beam splitter is set reasonably,the transmission of DP-RZ-16 QAM signal can be realized.