Compact, Efficient, and Robust Eyesafe Ladar Transmitter

The US Army has identified the need for a compact, lightweight, self-contained, electrically efficient, ruggedizable laser transmitter for 3-D imaging ladar applications. The transmitter cost, weight, footprint, and performance requirements (>5 W, 20-30 kHz, 5-20 ns) cannot be simultaneously met using current transmitter technology based on bulk Er, Ho, Tm lasers, OPOs, OPAs or Raman lasers. Conventional single-mode or large mode area (LMA) fiber lasers are limited by damage and parasitic nonlinear processes to peak powers well below those required in this program. Coherent Technologies, Inc. proposes a breakthrough approach to meet the transmitter requirements. The proposed transmitter implements a proprietary self-imaging process in a large core fiber to retain the high efficiency, diffraction-limited beam quality and excellent thermal handling of a single-mode fiber laser, while scaling the aperture to handle much higher peak power levels. A versatile master-oscillator power-amplifier (MOPA) architecture is adopted to meet the temporal format requirements without need for resonators or Q-switches. The self-imaging technique and MOPA architecture are leveraged by comprehensive demonstrations and by multiple other programs. The Phase I program has provided critical laboratory risk reduction demonstrations and developed a preliminary brassboard design to be developed, tested, and delivered on the Phase II program.