Large Aperture Micro-Electro-Mechanical Modulating Retro-Reflector Development

This proposal describes a project to design and manufacture large modulating retro-reflectors (MRRs) using Microelectromechanical Systems.(MEMS) optical modulators. The proposed MRRs have applications as intelligent nodes in space-based laser communication systems. In a Phase II project, Boston Micromachines Corporation (BMC) produced prototype MRRs with apertures of 25.4 mm. BMC also developed systems for testing critical modulator performance characteristics contrast ratio and temporal response in vacuum environments. Results of the Phase II effort uncovered manufacturing, assembly, and operational challenges that limit the technology readiness of MRRs for space-based applications. In the proposed Phase II.5 project, BMC will develop a new modulator fabrication approach that can improve manufacturing yield. This approach uses a single crystal material to replace the polycrystalline, defect-prone material used previously. Additionally, BMC will assemble and package MRRs in a sealed chamber that provides critical damping to the device, enabling it to perform in vacuum surroundings. Finally, BMC will enhance achievable contrast for the MRR device by incorporating modulators in all three facets of the MRR. This should significantly increase contrast, especially at high angles of incidence, in comparison to the single modulator devices prototyped in the Phase II effort.