Thin-film optical filters for selective transmission and black-body reflection in pyroelectric energy systems.

Essential to pyroelectric energy systems is the ability for a pyroelectric material to achieve high temperatures rapidly. In pursuit of augmenting this process, several thin-film optical filters were designed for transmitting laser excitation in the near-infrared region, while simultaneously reflecting black-body radiation for pyroelectric materials. Designs include a classical Fabry-Perot structure with gold and tantalum pentoxide, an induced transmittance filter with silica, hafnia, and gold, and an indium-tin-oxide filter with silica, alumina, and ITO. Performance varies depending on the design. The Fabry-Perot filter experimentally showed a maximum transmittance of 42% at 1.04 μm and an infrared reflectance of 98%. The induced transmittance filter was modeled to have a peak transmittance of 96% at 1.06 μm and an average infrared reflectance of 95% from 1.5 to 7.5 μm. Different ITO filters experimentally showed transmittance as high as 91.4% at 811 nm and reflectance as high as 92% at 8 μm.