Fabrication of sub-micron Thick, low loss As2S3 planar waveguides

Abstract

A chalcogenide glass (ChG) is one containing the chalcogen elements (Sulphur, Selenium or Tellerium) as a substantial constituent covalently bonded to network forming elements such as Germanium, Arsenic, or Antimony. ChG films are emerging as good candidates for integrated nonlinear optic (NLO) devices due to their high optical nonlinearities and low linear and nonlinear losses. We had already developed 2−3 micron thick As2S3 waveguides employing semiconductor processing [1] and demonstrated several NLO devices [2]. For more compact photonic integrated circuits, however, the device length reduction has to be compensated by boosting the waveguide nonlinearity coefficient, γ = (2π/λ)(n2/Aeff). The nonlinear refractive index, n2, is inherent to a material; hence the effective area of the light in the guide (Aeff) should be shrunk. This means the propagating light is to be confined tightly in the structure. The aim of this study, therefore, was to fabricate sub-micron thick, compact waveguides having low propagation loss.