Advanced 2-micron Solid State Laser Developments

The development of a space-qualifiable 2-micron laser is beneficial to both the Exploration and Earth science technology goals. Recently, significant advancements in the laser development have been made under the Laser Risk Reduction Program. One Joule per pulse energy was achieved by a Master-Oscillator-Power-Amplifier (MOPA) system. To our knowledge, it is the highest recorded energy at this wavelength. Fully conductive cooled 2-micron laser was demonstrated by the use of heat pipe technique. It enhanced the laser thermal management, and virtually eliminated the running coolant to increase the overall system efficiency and reliability. Direct pumped Ho laser, by taking the advantage of the commercial Tm fiber laser, is explored. It significantly increases the laser system efficiency and thermal performance. All these technical development efforts push forward the readiness of the space-borne coherent Doppler lidar. This paper will review the current state-of-the-art developments and the future technology challenges in the 2-micron solid-state lasers.