Demonstration of 1×32 LCOS-based wavelength selective switch

In recent years, reconfigurable optical add drop multiplexers (ROADM) and multiple-dimensions optical cross-connection (OXC), as the essential devices of next-generation dynamic optical networks, have been attracted great interests by research institutions and relevant industry. 1×N Wavelength selective switches (WSSs) are one of the key components in current and next generation ROADM. Currently, WSS primarily rely on micro-electromechanical systems (MEMS) and liquid crystal on silicon spatial light modulators (LCOS-SLM) switches. LCOS-based WSSs have several advantages, including flexible spectrum coverage, adaptive alignment, and robustness. Based on a novel 2-f optical structure, we therefore propose 1×32 WSS system including a 1×32 fiber-coupling lenslet arrays, a collimating lens, a transmission grating, a cylindrical lens and a LCOS-SLM. By uploading the optimized phased holograms on the LCOS, we have successfully switched input signal with arbitrary wavelength in C-band into any output port. The output channel spacing can be adjusted flexibly and each port switches independently. Experimental results demonstrate the insertion loss is around 5~10dB and the switch crosstalk at 1550nm is -35dB. The 3dB-bandwidth of signal@100G is 40G.The research has established the theory and experiment foundation for the development of M×N WSS in future.