Atomic Tailoring of the Solid State Materials for Laser Cryogenic Coolers
Abstract:
Erbium-based solid state materials are particularly important for low temperature laser cooling down to a few degrees Kelvin. This investigator proposed possible use of erbium-based solids for laser cooling. As of the date of this report, temperatures in bulk materials have been lowered by six degrees Kelvin from the ambient. This is an order of magnitude improvement and was achieved in atomically tailored materials. Such materials incorporated two to three orders of magnitude higher concentration of erbium than used by other groups. It is significant as the cooling was observed in the weakest transition of erbium. A much stronger 1.5 micron transition commonly used for lasers in communications, is expected to show correspondingly higher cooling efficiencies and lower cooling temperatures. Therefore, a thin film cooling device can be envisaged such as a diode laser pumping a thin film of erbium-based material. A device like this will bring laser refrigeration to cooling on a chip level, revolutionizing science and technology, and establishing a new paradigm for miniaturization of devices. This report describes progress of a comprehensive research program starting with theoretical calculations to predict the cooling efficiencies fabrication, growth and characterization of high concentration materials and most importantly performing experiments on laser cooling.