We present the theoretical analysis of a novel mechanical-contact-based submicron-Si-waveguide optical switch. The switch is composed of an identical input and output waveguides, and a movable waveguide driven by a miniature electrostatic comb actuator. The movable waveguide closes the gap between input and output waveguides. Due to mechanical-contact of submicron-Si-waveguides, input light propagates from input waveguide to output waveguide through the movable waveguide. The switch uses a transverse-electric-like polarized single-mode light at 1.55 urn telecommunication wavelength as the incident light. Theoretical calculations suggest that the optical switch with contact-tip waveguides at 45° tip angle can realize very sharp output signal change. As a result, 97.0 % transmission at the on state and 0.2 % transmission at the off state, corresponding to approximately 96.8 % optical output signal change between on and off states, are theoretically achieved by a displacement of 400 nm. Possible fabrication imperfections are estimated and their effects on the optical performance are calculated. Enlargement of all contact-tip surfaces is understood to be a promising approach for the switch performance enhancement against possible fabrication imperfections.
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