Variable gratings for optical switching: rigorous electromagnetic simulation and design

Ben-Gurion University of the NegevDepartment of Electrical andComputer EngineeringP.O. Box 653Beer-Sheva 84105IsraelE-mail: hava@bguee.bgu.ac.ilAbstract. This paper is devoted to rigorous electromagnetic diffractionanalysis, in the near infrared, for micromechanical silicon interdigitatedbeam gratings with both lateral and vertical displacement of movablebeams. In the wavelength-to-period ratio domain where the gratings sup-port three diffraction orders, the specific designs of high-efficiencyswitches for polarized radiation, such as switches from a transmitter to a133 transmission beamsplitter and from a retroreflector to an 1 32 re-flection beam divider, are presented. The possibility of light modulation,which follows from these designs, is discussed. The analysis with re-spect to wavelength, beam-width, beam-height, and incidence-anglevariations shows a good tolerance of the devices’ performance to spec-tral shifts and to fabrication and mounting errors. In addition, with the useof our software we simulated the diffraction efficiency versus displace-ment at a visible wavelength for a micromechanical grating reported inthe literature. There is good agreement between theory and experiment.