Multilayer As2Se3/GeS2 quarter wave structures for photonic applications

The optical properties of single layers from As2Se3 and GeS2, double-layered stack and quarter-wave multilayer structure consisting of alternating layers from both materials are investigated. For modelling of multilayer coating the thickness dependence of the refractive index of single coatings from both materials is studied. The particularities and scope of application of different spectrophotometric methods for calculation of optical parameters of thin chalcogenide layers are discussed for film thickness, d, in the range lambda/25-1.5 lambda (lambda being the operating wavelength). Having acquired the knowledge of optical parameters (refractive index, n, and extinction coefficient, k) of the single layers, we designed and produced a one-dimensional photonic crystal with fundamental reflection band at lambda = 850 nm. It was shown that the photoinduced changes of the refractive index of thin chalcogenide films can be used for enhancement of the optical contrast of both materials.