The Design Of DPSK Optical Modulation System

The requirements of communication speed and bandwidth from people improve quickly along with the rapid development of the global information science, communication systems are moving to the direction of large capacity, long-distance, high-speed, multi-channel transmission constantly. Studying the optical communication system make the transmission rate, and transmission distance of the communication system entered a new period. The large capacity, low loss, high sensitivity, long distance transmission relay and other excellent features, result in a large number of optical communication theory and technology which can meet the high requirements. This article focuses on differential phase shift keying(DPSK) Optical modulation system design, because of its high sensitivity, low error rate and other characteristics DPSK attracts lots of attention in recent years,and it is the modulation pattern which is used very widely. The design of optical modulation system based on DPSK studied in this paper mainly includes following contents:This paper introduces the history and research status of DPSK modulation pattern and optical modulation system, Studying and Discussing the advantages and characteristics of the optical phase modulator working in detail, as well as the Li Nb O3 modulator; Analyzing the generating process of DPSK optical modulation signal; several common optical modulation signal patterns were studied by Optisystem simulation tools, Analyzed and Compared several patterns combined with the simulation results; optical modulation system designed program based on DPSK modulation format, including the selection of required light source parameters and laser style; selection of a optical modulator and connections; drive control circuit design, including the control of output signal gain and percentage of eye crossing point voltage, and the design of differential coding circuit and the system power supply circuit; software design process for DPSK optical modulation system through Optisystem simulation software. Finally, considered the parameter settings of the simulation, set requirements of the system according to the parameters requirement and set up DPSK optical modulation system, Compared the experimental results with the simulation results and analyzed, confirming the system can be realized.The modulation rate of optical communication system which use DPSK modulation format is higher than most of the systems using other modulation methods, and the transmission distance is also farther than other modulation scheme. Therefore, Studying the design of optical modulation system which based on DPSK pattern is very meaningful.