Development of Solid-state Optical Cooler Materials to Replace Conventional Cryocoolers Usedfor Cooling SWIR and LWIR Infrared Detectors and Focal-plane-arrays

We propose an all-fiber approach to heat removal from devices such as IR and LWIR detectors and sensors. In our approach, the cooling fibersegment, the pump fiber laser, and the optical fiber used for photon waste removal are all integrated into a single fiber configuration. NPPhotonics' high efficiency fiber lasers are used to pump high purity doped glass fibers, which provide the cooling action on the affixed heatsource. Our system has several key advantages compared to conventional bulk glass systems. Its cooling power benefits from high opticalconfinement in the fiber core. Second, heat removal and waste photon piping into the fiber occur in the same location (the cooling fibersegment), increasing the fraction of heat that can be dumped at a remote location. Fiber Bragg gratings, which are transparent to the wastephotons and thus minimize fluorescence reabsorption, will be used for enhancing pump absorption. Based on NP Photonics' extensiveexperience in specialty glass and fibers, we will investigate laser cooling in Dy3+ doped glass. In Phase I, we will fabricate Dy3+-doped in bothtellurite and ZBLAN glasses. The glasses will be characterized to determine key parameters for IR fluorescent materials oriented to lasercooling using