Low-loss infrared dielectric material system for broadband dual-range omnidirectional reflectivity

A material system for broadband thermal IR applications based on branched polyethylene and tellurium is introduced. This system exhibits low absorption losses from 3.5 to 35 microm , has a large index contrast, and is readily deposited as a thin film. These unique features were used to investigate the formation of an omnidirectional reflector that exhibits two distinct, broadband omnidirectional ranges at thermal wavelengths. Reflectivity measurements are presented that confirm the existence of two omnidirectional ranges in the solar atmospheric windows extending from 8 to 12 microm and from 4.5 to 5.5 microm . The measurements are in good agreement with simulations.