Ultra-High Temporal Resolution Laser Radar (LADAR) Receiver

Voxtel will develop a prototype ultra-high temporal resolution flash LADAR receiver suitable for unmanned ground vehicle (UGV) or unmanned air vehicle (UAV) applications, based upon its low-excess-noise, multi-stage avalanche photodiode (APD) technology. During the Phase I program, 5-stage InGaAs APDs where shown to have a multiplication noise characterized by k=0.02 at a gain of M=20 (20× lower than the k-value of commercial InGaAs APDs), operation up to M=2000 (100× higher than commercial InGaAs APDs), and 500-ps pulse-pair resolution at a gain of M=100. Voxtel also demonstrated 10-stage InGaAs APDs of the same design which maintain silicon-like avalanche noise levels to a gain of M=1000. Efficient linear-mode single photon counting was performed with receivers assembled from the 10-stage APDs and commercial 2-GHz transimpedance amplifiers. In Phase II, Voxtel will optimize the multi-stage InGaAs APD structure for the best possible sensitivity at the eye-safe 1550-nm wavelength, develop a single-channel flash LADAR receiver chip capable of capturing eight pulse return samples per frame with 250-ps timing precision at frame rates up to 1.5 MHz, and demonstrate the resulting ultra-high temporal resolution flash LADAR receiver in a compact, fiber-coupled, and TEC-cooled package.