Research On Space Temperature Impact Of Tcfmzdi-based Dpsk Demodulation Performance

To solve the bottleneck problem of microwave communication data rate in satellite communications, satellite optical communication has become the development trend in the future satellite communications. Satellite optical communication, with the advantages of small-sized communication terminal, high communication data rate, good information confidentiality as well as strong anti-eavesdropping feature has been researched in technologically developed countries, some European countries, the United States and Japan, to name just a few. Achievement has been made in communication by the establishment of inter-satellite and the satellite-to-ground links and its application attempts to commerce have also been carried out.Differential phase shift keying (DPSK) is a modulation scheme of loading information by the difference between successive phases. Characterized by good tolerance for polarization mode dispersion (PMD), chromatic dispersion (CD), DPSK, at present, has found wide application in high-speed fiber-optic communication and to increase the communication capacity through dense wavelength division multiplexing (DWDM). Compared with the commonly used intensity modulation/demodulation (IM/DD) way, under the premise of same error rate, the DPSK format with balanced detection has "3dB" less in optical signal to noise ratio (OSNR) at the receiving end. Moreover, the DPSK boasts an edge in the satellite optical communication with a simple structure in the receiving end and similar sensitivity to homodyne coherent communications.The key part of DPSK lies in the interference demodulation at its receiving end. Since the current major demodulation device is fiber lbit delay interferometer (DI), which with fiber-type DI, like fiber-optic Mach-Zehnder is quite sensitive to temperature change, this will lead to the phase mismatch and consequently affect the communication quality. Given this defect, this thesis, based on twincore fiber (TCF) MZDI engages in the following work:First, an introduction is made on optical DPSK modulation, the basic principles and mathematical description of signal demodulation, as well as the demodulation parameters which influence the communication quality.Second, an analysis is carried out on the structure of TCFDI. A phase changing expression with the temperature varying and the temperature influence casting on the phase mismatch are explored. Third, based on TFC structure, a mode is further establishes to obtain the distribution of the temperature field, and calculate the corresponding phase mismatch under the conditions of external heat sources.Finally, the40Gb/s optical communication simulation system is built based on the Return to Zero (RZ) DPSK to get the Q parameter, eye diagram and bit error rate at the receiving end in the case of phase mismatch.