PI at ArkLight proposes a novel approach to photon counting detectors at near-IR (1-1.8 m) and mid-IR (3-4 m) with single photon sensitivity, representing an innovative Lidar technology for ASCENDS mission. She will convert the input signals at 1.27 m and 1.57 m to those at 579 nm and 634 nm, respectively, within a periodically-poled LiNbO3 wafer, pumped by a Nd:YAG laser at 1.064 m or a 200-mW InGaAs laser at 980 nm. The anticipated results for Phase 1 include demonstrations of efficient frequency up-conversion from 1.27 m and 1.57 m to 579 nm and 634 nm, determination of fundamental limits to noise equivalent powers, performance of the proposed detection system after optimizations, a final design of an ultra-compact detection system after considering e.g. an intracavity configuration, and reports. Beginning/end (Phase 1): TRL 1/3. The anticipated results for Phase 2 include implementation and testing of the ultra-compact detection system, measurement and analysis of noise equivalent powers and photon sensitivities, expansion of detection wavelengths to 1-1.8 m and 3-4 m, feasibility analysis of single-photon sensitivity, design, implementation, and testing of a battery-powered, cell-phone-sized, and integrable detection system with single photon sensitivity being achieved, to be tested in space-based platforms, and reports.