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

A material system for broadband thermal IR applications based on branched p olyethylene and tellurium is introduced. This system exhibits low absorptio n losses from 3.5 to 35 mum, has a large index contrast, and is readily dep osited as a thin film. These unique features were used to investigate the f ormation of an omnidirectional reflector that exhibits two distinct, broadb and omnidirectional ranges at thermal wavelengths. Reflectivity measurement s are presented that confirm the existence of two omnidirectional ranges in the solar atmospheric windows extending from 8 to 12 mum and from 4.5 to 5 .5 mum. The measurements are in good agreement with simulations. (C) 2001 O ptical Society of America.