Temperature resistant anti-reflective coating on Si-wafer for long-wave infra-red imaging.

A micromachined Silicon lid, sealed by CuSn solid liquid interdiffusion bonding is a promising approach for hermetic sealing of microbolometers for use in low-cost thermal cameras. However, since ∼30% of long-wave infrared light is reflected at an uncoated single Si-air interface, anti-reflective treatments are required. Traditional anti-reflective coatings are inapplicable since CuSn solid liquid interdiffusion bonding requires heating to about 270 °C and these multi-layer coatings fail due to differing coefficients of thermal expansion for the different layers and the substrate.

Design and fabrication of AsS-based non-quarterwave multi-cavity Fabry-Perot filters with the laser-adjustable central wavelength.

We present a thorough study of the use of AsS thin films for the fabrication of high-performance multi-cavity bandpass filters. We show that such layers can be used inside a non-quarterwave multi-cavity Fabry-Perot structure to produce local changes of the central wavelength of the filter using photosensitive properties of this material. In particular, we study the impact of these index changes on the spectral performances of the filters and show how to adapt the design of the Fabry-Perot structures to produce a spectral shift without degrading the bandpass profile.

High-performance thin-film optical filters with stress compensation.

We present a thorough description of high-performance thin-film optical filters with high flatness. These components can combine several tens or hundreds of layers and are manufactured using plasma-assisted reactive magnetron sputtering. Stress compensation is achieved using dual-side coatings with appropriate spectral function.

Athermal compensation of the stress-induced surface deflection of optical coatings using iso-admittance layers.

Mechanical stress in optical thin films can induce surface deflection of optical coatings. In the case of a substrate coated on both sides, a method is proposed which can provide perfect cancellation of this deflection, independently of the deposition process or any other external parameter, such as the temperature sensitivity of the mechanical stress. It is straightforward to implement this method, based on iso-admittance layers, since the thickness of such layers can be used to freely compensate for deflection effects only, without having any influence on the film's optical properties.

Phase properties of high-reflectance two-material periodic mirrors: application to oblique-incidence tunable filters.

Mathematical expressions are developed for the phase-shift derivative with respect to the wavelength, in the case of nonquarter-wave, two-material, high-reflectance, periodic mirrors. These expressions are applied to the case of oblique incidence, and a condition relating the layer indices, which provides identical phase dispersion curves for both the P and S polarizations, is derived. The use of such mirrors in Fabry-Perot filters results in a common peak wavelength for both polarizations when the filter is used at oblique incidence, instead of the two separate spectral peaks usually observed.