Moving reflector type micro optical switch for high-power transfer in a MEMS-based safety and arming system

Development of a moving reflector type micro optical switch fabricated by deep reactive ion etching (DRIE) in silicon on insulator (SOI) substrates is presented. The device discussed is a key component in a MEMS-based safety and arming (S&A) system for use in underwater weapons. In this switch, an etched vertical sidewall reflector is electrostatically actuated in and out of the optical path between input and output optical fibers. Fabrication is performed on 100 μm thick silicon substrates with fiber alignment channels, reflectors and actuators being fabricated at the same time with a single etch step. A single pair of multimode fibers is used to transmit optical power of the order of 1000 mW at a working wavelength of 810 nm. Sources of optical loss in the system are identified and their value calculated in order to predict the overall system optical efficiency. The optical efficiency of the switch has been found to have an average value of 55% with the etched vertical sidewall mirror having an average reflectivity of 62.8%. Switching time is 10 ms from the off to the on state with a maximum operational frequency of 60 Hz. Isolation between the on and off states is 32 dB.