Research On 1XN Port Wavelength Selective Switch Based On Silicon - Based Liquid Crystal Processing Chip

As the key fundamental equipment necessary for the future development of all-optical communication network, optical cross-connect (OXC) can be controlled remotely by software and Reconfigurable Optical Add-Drop Multiplexer (ROADM) have the extremely important research value and broad international market demand. They drew the attention of the device and equipment supplier and research institutions in the international scope. At present, the wavelength selective switch (WSS) is the core device of the third generation of ROADM. This paper analyzes the shortcomings of current WSS, such as the complex of optical structure, excessive insertion loss and crosstalk, the limited port number and number of channels and so on, then puts forward 1×32 wavelength selective switch with wide passband tuning flexibility based on liquid crystal on silicon (LCoS) by the software for remote control. Based on the optical scale diffraction theory, we established LCoS plane grating diffraction model and discussed the change law of 1st diffraction distribution and efficiency and the loaded LCoS phase hologram grating constant, rates for grating orientation and phase. Then on this basics, we apply LCoS processing chip to 1 ×N WSS in the system with fine 2f optical system and the special dispersion element, high precision optical fiber array and so on. Finally we completed a 1 X 32 WSS device schematic prototype. The results show that one or a set of wavelengths of dense wavelength division multiplexing (DWDM) in C-band can be smartly switched from the common port prototype to any output port of 32-port. Its channel bandwidth and channel spacing are arbitrary managed. Under standard 100GHz channel spacing, insertion loss of the 32 out-ports are as follows:the insertion loss of 1-20 port is 5-9dB,21-26 port is 6-15dB,27-32 port is 7-25dB; The wavelength crosstalk of each port is-15dB to-30dB; The channel space of 3dB-band width wavelength is 40 GHz and the minimum space is 50GHz. The works are conducive to the study of M×N wavelength selective switch.