Polarization insensitive silicon immersion grating based on total internal reflection.

We describe an immersion grating (IG) with both low polarization-dependent loss (PDL) and high diffraction efficiency. Our immersion grating consists of a silicon (Si) prism and a Si grating coated with dielectric film. We analyze the effect of the refractive index of dielectric film and clarify the refractive index ratio between a Si grating and dielectric film. Selecting an adequate material for the dielectric film, we design the diffraction efficiency of TM polarization without changing that of TE polarization. The simulation results for the optimized IG show a PDL of 0.2 dB and diffraction efficiency of -0.4 dB. A prototype with high dispersion power provides a low PDL of 0.6 dB, while maintaining a high diffraction efficiency of -0.4 dB.

128×128 three-dimensional MEMS optical switch module with simultaneous optical path connection for optical cross-connect systems.

A 128×128 three-dimensional MEMS optical switch module and a switching-control algorithm for high-speed connection and optical power stabilization are described. A prototype switch module enables the simultaneous switching of all optical paths. The insertion loss is less than 4.6 dB and is 2.3 dB on average. The switching time is less than 38 ms and is 8 ms on average. We confirmed that the maximum optical power can be obtained and optical power stabilization control is possible. The results confirm that the module is suitable for practical use in optical cross-connect systems.