Observation of Optical Refrigeration in a Holmium-doped Crystal

Abstract

We report the first demonstration of solid-state optical refrigeration of a Ho-doped material. A 1 mol% Ho-doped Yttrium Lithium Fluoride (YLF) crystal is cooled by mid-IR laser radiation, and its external quantum efficiency and parasitic background absorption are evaluated. Using detailed temperature-dependent spectroscopic analysis the minimum achievable temperature of a 1% Ho:YLF sample is estimated. Owing to its narrower ground- and excited-state manifolds, larger absorption cross-section, and coincidence of optimum cooling wavelength of 2070 nm with commercially available high-power and highly efficient Tm-fiber lasers, Ho^3+-doped crystals are superior to Tm^3+-doped systems for mid-IR optical refrigeration. With further improvement in material purity and increased doping concentration, they offer great potential towards enhancing the cooling efficiency nearly two-fold over the best current Yb:YLF systems, achieving lower temperatures as well as for realization of eye-safe mid-IR high-power radiation balanced lasers.

arXiv comment14 pages, 4 figures

References in corpus (2)

• A sub-40 mHz linewidth laser based on a silicon single-crystal optical cavity
• Anti-Stokes laser cooling in bulk Erbium-doped materials

Cited by in corpus (5)

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• Heat Evacuation from Active Raman Media Heat Evacuation from Active Raman Media Using Quasi-PT Symmetry Coupling
• Purcell-enhanced optical refrigeration
• Purcell Enhancement and Suppression in Laser Cooling of Yb${}^{3+}$:YLF Nanocrystals in a Fabry-Pérot Microcavity