Self-tuned Fabry-Perot spatial light modulators

A key component of free space optical interconnect systems is a spatial light modulator (SLM). SLMs are two-dimensional arrays that impart electrical signals onto an optical beam. The subject of this research is the development of surface-normal SLMs having good spatial uniformity and contrast ratio while being driven by small electrical voltages suitable with silicon circuits. This can be accomplished using the electrooptic material PUT within a novel structure call a self-tuned Fabry-Perot (STFP). The STFP structure is created by replacing the input mirror of a conventional Fabry-Perot electrooptic modulator with a holographic material. Recording the hologram in-situ allows for non-uniformly thick electrooptic materials to be used for modulation.; The thickness compensating effect of the STFP structure was described with a basic theoretical treatment and verified experimentally. A detailed optical model was embodied in an interactive computer program to understand the tradeoffs of the STFP parameters on performance. The model was used to optimize the holographic material properties, resulting in a 2mm thick reflection-mode photorefractive LiNbO3:Fe crystal having high diffraction efficiency (70%) and low absorption (1.8cm-1).; The STFP concept was also applied to an array of bulk PLZT modulators and stamped epoxy lenslets. An 8 x 8 STFP array exhibited uniform, low noise and good contrast ratio images, whereas the conventional Fabry-Perot array showed excessive distortion and very poor uniformity. The STFP concept was also demonstrated with a thin electrooptic material, a PLZT wafer thinned to 22mum. High contrast and uniform intensity modulation over a 5mm aperture were obtained, in sharp contrast to the equivalent conventional modulator. In addition to the investigation of thinned PLZT STFP SLMs, significant effort was made in characterizing prospective magnetron-sputtered PLZT thin films for the application to STFP devices. This enabled advancements of the film deposition process, resulting in good quality PLZT 9/65/35 films; however, the electrooptic properties of the films varied too substantially to be practical for STFP devices.; Improving the reflectivity of holographic mirrors over a wider light spectrum range, especially at 850nm and 1300nm, STFP structures may find applications in additional optical devices, e.g. multiple quantum well light modulator arrays.