Emerging Trends, Challenges, and Applications in Solid‐State Laser Cooling

Summary

Laser‐induced cooling or optical refrigeration of materials relies upon anti‐Stokes fluorescence in which phonons are removed as radiation to induce cooling. The motivation for the development of this technology is to tackle the practical complications encountered in the currently available cooling techniques, like microphonic vibrations, need for electrical connections, physical heat dissipation, etc. Optical refrigeration may overcome these practical difficulties with its features such as lack of vibrations (other than molecular vibrations), no mobile parts, reliability, reduced electromagnetic interference, and longer lifetime. Currently, new trends and innovations are emerging rapidly, driving the future of laser cooling to new horizons in both theory and applications. However, most of the research in optical refrigeration has been focused on materials that are difficult to manufacture, to handle, and to merge in a wide variety of instruments. Therefore, there is a pressing demand for the development of alternatives.

Rare earth doped oxyfluoride glass ceramics‐based materials for cooling is attracting interest in the scientific community for several reasons. First, rare earth ions are preferably embedded into the fluoride nanocrystalline environment, benefiting them from their low phonon energy environment, compared to the high phonon energy of oxide vitreous host. Second, glass ceramics are generally produced directly from glassy materials, which are robust, easily moulded and cheap to manufacture, therefore offering significant advantages for the practical implementation of solid state laser coolers. Successful cooling with these novel glasses and glass ceramics will open new avenues in laser cooling research, making it easier to cool devices with any geometry. This chapter complies and details recent development in solid‐state laser cooling technology, especially in the field of oxyfluoride glass ceramics. The progress in solid‐state laser cooling using different materials along with the design and production of optical cryocoolers are briefly explained.