Hemispherical Emittance of a Semitransparent Fiber Coated With a Submicron Absorbing Film Available to Purchase

This study presents a model to predict the directional and hemispherical emittance of a fiber coated with up to 2 μm film. The fiber is composed of semitransparent media with a small extinction coefficient. Transmittance and reflectance of the thin film is calculated based on the flat thin film assumption, because the thickness of the film is much less than the fiber radius, and the curvature can be neglected. Predicted emittance from wave optics is compared to geometric optics for modeling radiative transfer in thin film. Steep changes in emittance are predicted by wave optics for films that are nanometers thick. This effect was not observed from geometric optics analysis. Effects of film and fiber substrate optical properties are also studied.