III-V materials-based optical-MEMS devices for adaptive optics and vibration sensing

Two novel III-V-based optical MEMS were designed and demonstrated. The first is an optically controlled micro-mirror array MEMS (OC-MEMS) and the second is a novel cantilevered-waveguide vibration sensor/optical switch MEM device. Arrays of OC-MEMS elements in configurations as high as 30 x 30 elements were fabricated using capacitance driven Si3N4 spring plate mirrors integrated with GaAs photo diodes that were fusion bonded to transparent GaP substrates. In these devices an optical signal focused on an element's p-i-n diode through the GaP substrate changes the ratio of the voltage across a load resistor allowing the spring plate capacitor to charge which in turn changes the position of the micro-mirror. Control signals as low as 100 microwatts cause the mirror to move sufficiently to change the phase of a reflected signal by half a wavelength, thereby providing a phase change to the reflected beam at that element. A unique feature of this architecture is that only one voltage bias line is needed, independent of the number of array elements since the control function has been moved to optical control beams. Such OC-MEMS are well suited for image phase correction. Novel cantilevered optical waveguide vibration/optical switch MEM devices were fabricated and figures of merit measured. Here, ridge waveguides in the AIGaAs materials system were grown and tabricated into devices where the substrate was removed under a portion of the guide and the guide cut at one end of this "bridge" to form a cantilevered bean. As part of the effort finite element models using novel techniques to aid in the design and performance predictions of the various multiphysics interactions in the OC-MEMS and the cantilever devices were developed.