MEMS-based variable optical interference devices

Abstract

We discuss our so-called MARS (mechanical anti-reflection switch) devices, in which the membranes in the first devices have the same thickness and refractive index as an anti-reflection coating. By varying the air gap between odd and even multiples of /spl lambda//4 the reflectivity goes from high to near zero. This can be easily understood since if the air gap is zero it is of anti-reflecting and if it is /spl lambda//4 a high reflector mirror stack is formed, and since in any optical stack the reflectivity at the center wavelength is independent of additions of /spl lambda//2 to any layer. Six devices are described that only require variations on the layer structure of this simple mechanical structure, including changes in refractive index and thickness and additional layers. These are the simple data modulator requiring only on and off states, and the design methodology for trading insertion loss for wavelength range, a linear response device for producing harmonic signals, an attenuator requiring variable reflectivity that is independent of wavelength, a multi-electrode wavelength power equalizer, a gain slope compensator that has variable spectral tilt without attenuation changes, and a display design for operation over the entire visible spectrum.