Silver halide planar waveguides and grating couplers for middle infrared integrated optics

We fabricated silver bromide (AgBr) planar waveguides with a thickness of approximate to 20 mu m and designed reflective grating couplers for coupling the radiation of a tunable CO(2) laser into these waveguides. We found that the attenuation was 6-9 dB/cm. The waveguides were used as attenuated total reflection elements for the sensing of hazardous pesticides in water in concentrations higher than 25 ppm. This work will pave the way for developing integrated optical elements and circuits which are based on silver halides and which operate in a broad spectral range in the mid-IR. These will be useful as chemical sensors and as spatial elements in nulling interferometry. (C) 2010 American Institute of Physics. [doi:10.1063/1.3527920]