Design and characterisation of a low-power micromachined spatial light modulator

The MEMS spatial modulator proposed in this paper consists of a silicon element coated with a gold reflective layer. The silicon element is supported in the centre of a silicon nitride membrane and a platinum heater is used to control the temperature of the silicon and gold films. Increasing the temperature of the materials encompassed by the heater induces distortions analogous to those produced by heating a bimetallic beam fixed at both ends. To investigate these distortions, a 3-dimensional model of the membrane and the overlay components was constructed with ANSYS finite element software. Analysis of the results generated showed that a half-wavelength phase shift was obtainable with power consumptions less than 10 mW.