PI at ArkLight proposes a novel approach to photon counting detectors at near-IR (1-1.8 µm) and mid-IR (3-4 µm) with single photon sensitivity, representing an innovative Lidar technology for ASCENDS mission. She will convert the input signals at 1.27 µm and 1.57 µm to those at 579 nm and 634 nm, respectively, within a periodically-poled LiNbO3 wafer, pumped by a Nd:YAG laser at 1.064 µm 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 µm and 1.57 µm 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 µm and 3-4 µm, 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.