Design and Fabrication of an Optical-MEMS Sensor

Abstract

A novel optical-MEMS sensor based on the AlGaAs material system is designed and fabricated. The device consists of micro-beam waveguides butt-coupled with their ends separated by approximately 2 to 4 µm. The device works on the principle that when acoustically driven by an external source, the waveguides misalign, leading to coupling loss. The device design parameters were determined using FEM (Finite Element Method) modeling. The dielectric waveguide beams were designed for single mode propagation at 785 nm and longer wavelengths. A combination of dry and wet etching process followed by precision laser cutting was used to fabricate the suspended beams. Beams ranging from 100 µm to 400 µm with fundamental frequencies of 50 KHz to 200 KHz were successfully fabricated. Initial uncut waveguide test results will be discussed along with the plan for characterizing the devices using an acoustically coupled piezoelectric driver. These devices may be utilized for vibration sensing, or optical intensity modulation.