Polysilicon micromechanical gratings for optical modulation

Abstract

Vertically and laterally moving surface-micromachined polysilicon microelectromechanical gratings have been designed for optical switching and modulation applications. Analytical models for the gratings are developed using optical diffraction theory. Example gratings have been fabricated in the ARPA sponsored Multi-User MEMS Process (MUMPS), and test results of the fabricated gratings are shown to have good agreement with the model. The vertically moving grating achieved an 18.1 dB contrast ratio between maximum and minimum intensity of the first diffracted order with a drive voltage of only 3 V at modulation rates up to 110 kHz, making it an excellent candidate for an optical switch. The laterally moving grating is demonstrated as a switch for transferring energy between the first and second diffracted orders, achieving modulation intensities of 6.4 dB for the m = 1 and 9.0 dB for the m = 2 diffraction orders.