Variable gratings for optical switching: rigorous electromagnetic simulation and design

This paper is devoted to rigorous electromagnetic diffraction analysis, in the near infrared, for micromechanical silicon interdigitated beam gratings with both lateral and vertical displacement of movable beams. In the wavel ength-to-period ratio domain where the gratings support three diffraction o rders, the specific designs of high-efficiency switches for polarized radia tion, such as switches from a transmitter to a 1x3 transmission beamsplitte r and from a retroreflector to an 1x2 reflection beam divider, are presente d. The possibility of light modulation, which follows from these designs, i s discussed. The analysis with respect to wavelength, beam-width, beam-heig ht, and incidence-angle variations shows a good tolerance of the devices' p erformance to spectral shifts and to fabrication and mounting errors. In ad dition, with the use of our software we simulated the diffraction efficienc y versus displacement at a visible wavelength for a micromechanical grating reported in the literature. There is good agreement between theory and exp eriment. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S009 1-3286(99)01803-6].