Advances in Raman-based broadband optical refrigeration

Raman optical cooling has been observed in structured fiber optics designed to enhance the Raman anti-Stokes emission through resonance. However, these approaches are not amenable to large area cooling under a portion of the solar spectrum. This work explores the use of planar structures to increase cooling efficiency, increase device area, broaden the working wavelength band, and reduce cost. Simple, planar structure require optical thin Raman shift layers. Since, so that a simple quarter-wave or series of quarter-wave reflector can be engineered to suppress the heat releasing Stoke's shifted light. In-turn the main material challenges associated with similar to 10 nm crystalline films is the requirement for at least one dimension of the film to support domains (grain sizes) large enough to support the phonons needed for Raman scattering. As expected ten nanometer diamond particles do not appear to support the bulk-crystal phonon modes responsible for the 1332 cm(-1) Raman shift suggesting new material approaches. A new scalable approach is presented and in parallel new applications such as water vapor recovery by cooling explored.