In this effort, Radiation Monitoring Devices, Inc. (RMD) addresses NASA's request for sensitive, high quantum efficiency (QE) optical detectors for space- and ground-based light detection and ranging (Lidar) instruments. We propose to address this need by utilizing our latest designs in solid state photodetectors, and providing optimal receiver solutions needed for NASA's ongoing and future science missions. The solid state photodetectors that will be evaluated for this program will include RMD's large-area, high-gain proportional mode avalanche photodiodes (APD). The focus will be on modification of RMD's existing structure to improve responsivity and bandwidth in the blue and ultra-violet (UV) region of the spectrum. Preliminary studies have shown that UV responsivity and bandwidth of our large area detectors can be increased through the application of a modified surface layer using a well-established processing method. The proposed receiver technology readiness level (TRL) is estimated at 2. The Phase I effort will utilize experimental and theoretical studies to confirm the feasibility of the defined approach, resulting in a prototype design with a TRL of 3-4. In Phase II, the prototype receiver will be fabricated and evaluated. A TRL of 5-6 will be reached by the end of this SBIR program.