A Silicon Spatial Light Modulator Unit With High Extinction Ratios in C Band

A spatial light modulator (SLM) unit by using polycrystalline silicon (poly-Si) as resonant thin film is demonstrated here in order to improve the extinction ratios in C band (1530 to 1565 nm). The curves of the reflectivity of SLM unit versus wavelength with voltage OFF and ON are simulated and verified by experiments. The SLM unit presents high extinction ratios in C band with maximum of 42.2 dB at 1547.5 nm. The high extinction ratio is due not only to the excellent thermo-optic effect but also to the thermo-elastic deformation effect of the poly-Si thin film. The resonance wavelength has a red shift of 2 nm. The high-extinction-ratio C-band spatial light modulator unit has a giant application potential in the space optical communication field.