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Silica glass is an extremely useful material with excellent optical and mechanical properties, that is easily shaped into a wide variety of forms. Unfortunately, due to the high phonon energy of silica, it has been a challenge to use it for laser cooling applications as it requires ultrahigh purity to avoid parasitic heating adding to the non-radiative pathways, and which act as a severe heat load in any cooling event. Our research over the years has focused on trying to incorporate rare earth materials in silica glass for example, in the form of nanocrystals of fluoride through heat treatment, which provide a low phonon environment, thus shielding it from the high phonon energy silica host. As opposed to the untreated glasses, which showed significant heating, this approach resulted in near zero temperature rise. However, this route as well, is an arduous one as purification of the starting materials is still an issue for the casting technique used for glass manufacture. Recently, our work has focused on inducing phase separation of active rare earth oxides in an environment of a non-active rare earth oxides, such as yttrium oxide to form a unique glass. We have shown that through temperature control, the phase separation of RE: yttria can be either enhanced or reversed, transitioning from clear to turbid to clear glass states using a high purity MCVD process. Our work led to the largest successful cooling reported to date of GAYY-PS oxide glass by with a temperature drop of 4 K from the ambient. This presentation reviews these developments and subsequent progress of laser cooling and other applications in these novel and highly promising glasses.
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