Hybrid electric and optical detector for selected gas in ambient atmosphere has thin layer of material whose refractive index and/or conductivity is affected by gas to be detected

摘要

A detector (3) contains a thin layer (8) of material sensitive to the gas, allowing an optical wave (11a) to pass through it from an optical wave source (1). The refractive index (n, N) of the material and/or its electrical conductivity vary under the effect of the gas, so a means of evaluating the presence of the gas can detect and preferably measure these perturbations. The means of revealing the electrical conductivity of the thin layer extend from a first zone in the thin layer next to a second zone which is reserved to receive the optical wave and ensure optical connection to the optical detector. The detector contains, stacked together, a substrate, means of revealing the conductivity of the thin layer, and the thin layer which is sensitive to the gas being detected. The means of revealing the conductivity of the thin layer are a network of interposed electrodes. The thin layer includes a material active as a wave guide when it is lit by the optical wave. The device also includes means (15) of optical coupling between the optical source and the detector: this optical coupling is a prism, a wave guide in an interferometer or a diffraction grating. The means of detecting perturbations in the optical wave due to variations in refractive index include elements of detecting variations in transmission and/or reflection of the wave in the detector under the effect of the selected gas. These can be means of measuring the optical wave flow, an interferometer or means of measuring the deviation of the optical wave in the detector. The first and second zones in the thin material are juxtaposed on a common substrate. The material of the thin layer forms a wave guide or the detector also contains a wave guide layer (9). An independent claim is included for detecting at least one selected gas in an ambient atmosphere using the above detector, where the hybrid detector is exposed to an atmosphere which may contain the selected gas and the perturbation in the refractive index and/or electrical conductivity of the thin layer caused by exposure to the gas is detected and preferably measured.