Advanced Packaging for Cryogenic Spray Cooled Laser Diodes Arrays

Laser diode bars have demonstrated ultra high electro-optical efficiencies >80% when operated at cryogenic temperatures <150 K. Diode pumped-solid-state lasers utilizing cryogenically cooled laser diode arrays and gain material have the potential to increase the wall plug efficiencies to values over 40% compared to 10% for room temperature lasers. To realize these exceptionally high laser bar efficiencies a unique cryogenic cooling approach will be developed. In the proposed SBIR program RTI will: 1) utilize Spray Cooling with liquid nitrogen to show feasibility of cooling a cryo-diode laser array with an optical flux of 560 W/cm2, 2) establish the feasibility by design and experiment for a diode package tolerant of cryo temperatures by using innovative CTE matched material combinations, and 3) partner with diode vendors to construct a spray cooled, CTE matched diode array that will undergo mechanical temperature cycling tests to validate the design.