This Phase-I SBIR proposal directly addresses the need to improve the size, weight and power, SWaP, of optical cryocoolers. In particular, the proposers will work toward increasing the efficiency of optical cryocoolers by incorporating cooling materials that require less input laser power to achieve a given heat lift. The new cooling materials will be high-purity crystals doped with active rare-earth ions that are efficient cooling agents. The proposers will acquire and characterize these materials. Additionally, they will design and construct components of a cooling device directed toward cryogenic cooling.