Lasers with a Cool Touch
Start Date
8-11-2017 1:30 PM
End Date
8-11-2017 5:30 PM
Abstract
This research is focused on making lasers without internal waste heat. Lasers have become important light sources, not only for research, but also industrial, medical, and defense applications. Like any other devices, they generate waste heat, which ultimately limits their performance, beam quality and output power. In the last several years, great progress has been made in optical refrigeration of solids, where a laser is used to cool several rare-earth doped crystals (Yb:YLF, Tm:YLF, Tm:BYF, and Ho:YLF) via a process called anti-Stokes fluorescence. On average, each emitted fluorescence photon has slightly more energy than the absorbed pump photon, and therefore carries away heat from the crystal. Using these cooling materials as active media in optically pumped lasers, one can balance the cooling process with the heat-generating lasing action, creating a radiation balanced laser (RBL) – cool to the touch. By cooling the crystal in the same location where heat is generated, this greatly reduces thermal gradients present in traditional heatsinking schemes, improving the output beam quality and laser stability. After recently observing laser cooling in Tm and Ho doped crystals and demonstrating RBL in Yb doped crystals, we are modelling and designing a mid-infrared RBL version for operation near 1900 nm. Using our measured material parameters, incident pump power, laser output power and wavelength should be carefully balanced to achieve RBL operation.
Lasers with a Cool Touch
This research is focused on making lasers without internal waste heat. Lasers have become important light sources, not only for research, but also industrial, medical, and defense applications. Like any other devices, they generate waste heat, which ultimately limits their performance, beam quality and output power. In the last several years, great progress has been made in optical refrigeration of solids, where a laser is used to cool several rare-earth doped crystals (Yb:YLF, Tm:YLF, Tm:BYF, and Ho:YLF) via a process called anti-Stokes fluorescence. On average, each emitted fluorescence photon has slightly more energy than the absorbed pump photon, and therefore carries away heat from the crystal. Using these cooling materials as active media in optically pumped lasers, one can balance the cooling process with the heat-generating lasing action, creating a radiation balanced laser (RBL) – cool to the touch. By cooling the crystal in the same location where heat is generated, this greatly reduces thermal gradients present in traditional heatsinking schemes, improving the output beam quality and laser stability. After recently observing laser cooling in Tm and Ho doped crystals and demonstrating RBL in Yb doped crystals, we are modelling and designing a mid-infrared RBL version for operation near 1900 nm. Using our measured material parameters, incident pump power, laser output power and wavelength should be carefully balanced to achieve RBL operation.
