Abstract

Chalcogenide glasses (ChG) have been shown to be very promising for application in integrated guided wave devices and infrared telecommunication systems. High optical transparency in the near and far infrared region as well as large optical nonlinearity are two important and attractive properties for using these materials in linear and nonlinear integrated optical elements. It has also been found that the chalcogenide glasses are photosensitive to near band gap illumination (E_g= 2.35 eV). Thin films of ChG exposed to near band gap light have exhibited photostructural changes both in the volume (photodarkening, refractive index changes), and in the surface (photoexpansion, densification). On the other hand, the photoexpansion induces a surface deformation which can also change the optical properties of the material. Both of these effects contribute to increasing the refractive index of ChG allowing us to pattern different photoinduced guided wave structures in ChG thin films. In particular, we present here for the first time to our knowledge, the fabrication of stable and efficient Bragg gratings in single mode As₂S₃ ChG planar waveguides with near band gap illumination. These gratings can be used to act as wavelength selective components in WDM optical circuits.

© 1998 IEEE