Study On LCoS Based Wavelength Selective Switch And Multi-Wavelength Fiber Lasers

All-optical communication network has the advantages of high reliability, low cost, high scalability, flexible networking, intelligent allocation of cyber source dynamic and many other advantages, intelligent communication optoelectronic devices, optical switching and optical cross connect technology has become a hot topic in the field of optical communication. Remote-controlled tunable multi-wavelength fiber laser (TFL)、 Wavelength Selective Switch (WSS) and reconfigurable optical add drop multiplexer (ROADM) are the key basic equipment of future development of all-optical communication network. These techniques have attracted many domestic and foreign research institutions and obtained manufacturers’attention, which also have a broad market demand and important research value. (WSS) is the core component of the third generation of ROADM.In this paper, we proposed a WSS with flexible passband regulating function. This kind of WSS is based on liquid crystal on silicon (LCoS) chip and can be controlled within a long distance. By using the flexible filtering function of the WSS, we proposed a new type of multi wavelength fiber laser based on LCoS, in which flexible, stable and tunable light with multi wavelength can be obtained only with a piece of LCoS chip. Detailed contents are as follows:(1) The research advances of liquid crystal on silicon spatial light modulator (LCoS-SLM) and the study of multi wavelength fiber laser are introduced. Then the electro-optic characteristics of the liquid crystal and the diagram concept of the LCoS-SLM have been analyzed. Different polarization states and light intensity of output light throughout the liquid crystal are calculated by the theory of Jones Matrix.(2) Through the analysis of scalar diffraction theory, the diffraction efficiency of LCoS-SLM with loaded phase grating hologram has been discussed. Finally, the expression of diffraction efficiency has been calculated and diffraction intensity curves have been simulated by using the method of spatial domain and frequency domain.(3) On the basis of theoretical analysis, by applying the LCoS chip into the WSS system, incorporating with optical devices like special dispersion components and high precision optical fiber port array, etc. This kind of WSS is reasonable-structured, flexible and interval adjustable.(4) Based on the filter characteristics of the WSS, we build an experimental platform of multiple wavelength tunable fiber laser based on LCoS. Then four stable wavelength lasing is demonstrated at the room temperature. Each wavelength can be tuned independently. The wavelength interval of the output laser light is 4 nm and the mold inhibition ratio (SMSR) is more than 50dB.