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Recent experimental breakthroughs in the laser-refrigeration-of-solids (LRS) have demonstrated that cryogenic temperatures can now be achieved opening up a range of promising applications using compact, vibration-free optical cryocoolers. These results also have stimulated significant interest in the development of new material designs for applications in radiation balanced lasing (RBL). The development of practical host materials for RBLs requires the understanding of how both spontaneous emission rates and non-radiative decay rates change under a wide range of thermal conditions and dielectric host environments. In this work the photoluminescence lifetime of 4S3/2 transitions from Er(III) ions within co-doped Yb3+/Er3+-codoped hexagonal sodium-yttrium-fluoride (beta-NaYF4) nanostructures is presented as a rapid, low-cost, spatially resolved method of quantifying the temperature of within RBL materials. Lifetime measurements from single nanostructures are made using single-beam laser-traps, where the focal plane of the trapping laser is used to control the spacing between single nanowires and dielectric chamber surfaces that are supported by a temperature-controlled piezo-stage. The lifetime of Er(III) ions is observed to change significantly based on the distance between emitting dipoles and nearby dielectric interfaces and also as a function of chamber temperature. Lifetime measurements are also presented for measuring the temperature within polydimenthylsiloxane-polymer/nanocrystal composite materials that serve as a model system for future optical-fiber cladding materials. Lastly, ratiometric photoluminescence and lifetime measurements will be presented for Yb(III):YLiF4 microcrystals supported on cadmium sulfide nanoribbon cantilevers, indicating the potential for hybrid semiconductor/RE-fluoride composite structures for future RBL applications.
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