In this article, we study the thermal light emission from individual fibers of an industrial glass material, which are elementary building blocks of glass wool boards used for thermal insulation. Thermal emission spectra of single fibers of various diameters partially suspended on air are measured in the far field by means of infrared spatial modulation spectroscopy. These experimental spectra are compared with the theoretical absorption efficiency spectra of cylindrical shaped fibers calculated analytically in the framework of Mie theory taking as an input the measured permittivity of the industrial glass material. An excellent qualitative agreement is found between the measured thermal radiation spectra and the theoretical absorption efficiency spectra.

In this work, we propose an experimental set-up to measure the thermal conductivity and specific heat of a single suspended glass fiber, as well as the thermal contact resistance between two glass fibers. By using optical lithography, wet and dry etching and thin film deposition, we prepared suspended glass fibers that are coated by niobium nitride thin film (NbN) used as room temperature thermal transducer. By using the 3ω technique, the thermal conductivity of glass fiber was measured to be 1.1 W.m-1.K-1 and specific heat 0.79 J.g-1.K-1 around 300 K under vacuum conditions. By introducing exchange gas into the measurement chamber, influence of the gas on the heat transfer was studied, and the convection coefficient h for all the measurement ranges from a pressure of 0.01 hPa to 1000 hPa, over more than five orders of magnitude, has been obtained. By adding a bridging glass fiber on top of two other suspended glass fibers, it was possible to estimate the thermal contact resistance between two glass fibers Rc in the range of 107 K.W-1 to 108 K.W-1.