1.65um Pulsed Laser for Space Based Winds

Fibertek, Inc. will develop a single-frequency, Er:YAG laser transmitter to advance the technological readiness level (TRL) of a key technology component of the 3D wind measurements identified in the recent Earth science decadal survey “Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space”. The Er:YAG development will advance the technology of a space-based wind lidar system by focusing on developing a compact, efficient diode pumped transmitter that is conductively cooled. Current efficient 2µm systems are pumped by fiber lasers to take advantage of the high brightness source, but this tends to increase the packaging foot print. To maintain long pulsewidths >100ns, the 2µm systems cavities are typically greater than 2 meters in length. By working at higher repetition rates (500Hz or above) than are typically targeted in 2µm systems, Fibertek will take advantage of the long storage time of Er:YAG to maintain efficient operation, while operating at longer pulse lengths in a shorter cavity (with respect to Ho:YLF systems of similar pulse lengths) due to the low gain of the Er:YAG. Fibertek’s approach will be based on an Er:YAG resonator operating at 1645nm and resonantly pumped by high brightness semiconductor laser diodes.This program will build on successful Er:YAG work at Fibertek focused on methane and water vapor lidars. These systems are 7-10W systems optimized for operation at higher repetition rates. The Phase I work will demonstrate a high power (>12.5W) oscillator optimized for 500Hz operation with a Technology Readiness Level 4 (TRL-4) for a coherent wind lidar. In Phase II we will develop a hardened brassboard version of the laser that would be suitable for airborne systems. We will also perform a trade study on how to achieve the highest damage threshold coatings at 1.6455 µm.