Improved omnidirectional reflectors in chalcogenide glass and polymer by using the silver doping technique

We describe the fabrication and characterization of omnidirectional reflectors based on silver-doped chalcogenide glass and polymer. We deposited periodically alternating layers of thermally evaporated Ge33As12Se55 chalcogenide glass, sputtered silver, and spun-cast polyamide-imide polymer. The silver was subsequently dissolved into each adjacent chalcogenide glass layer, either by exposing the multilayer to visible light (photodoping) or by heating the sample. The resultant silver concentration within the chalcogenide glass layers is estimated to be similar to 20 at. %. Silver doping red-shifts the band edge of the glass, and produces an increase of similar to 0.3-0.4 in the refractive index. The glass retains good transparency in the near infrared after doping, and the technique enables the omnidirectional bandwidth to be increased from similar to 100 nm to similar to 200 nm in the 1550 nm wavelength region. (c) 2005 Optical Society of America.