Fabrication of rib waveguides and optical fibres in chalcogenide glasses

Lian, Zheng Gang

Fabrication of rib waveguides and optical fibres in chalcogenide glasses

Publication Date

July 18, 2011

Creator

Lian, Zheng Gang

Abstract

Chalcogenide glasses offer transmission from the far visible to the far - infrared (IR) wavelength range. They exhibit photosensitivity and have high linear and nonlinear refractive indices. There are many potential applications involving near- and mid- infrared light such as laser delivery, optical data storage and all-optical switching. Two types of optical waveguides based on chalcogenide glasses were developed in this project: (1) The fabrication of planar optical waveguides in thin As40Se60 glass films was carried out via a hot embossing pressing technique. Previous work had shown it possible to fabricate optical waveguides in polymers using hot embossing techniques. Nevertheless using hot embossing to pattern waveguides in a thin chalcogenide glass film did not receive much success. In the present work, single-mode optical rib waveguides operating at telecommunication wavelengths were successfully patterned in a thermally evaporated As40Se60 glass thin film on a Ge17As18Se65 chalcogenide glass substrate. This experimental line demonstrated a fast and economic way of producing planar waveguides in thin chalcogenide glass films. (2) For the first time, a one-layer, solid micro-structured optical fibre (MOF) was successfully drawn from As40Se60 and Ge10As23.4Se66.6 (atomic %) chalcogenide glasses for operation in the near- to mid-infrared. This experimental line showed a new and flexible route to micro-structuring of mid-infrared fibre for operation in the near- to mid-infrared, presenting an all-solid (i.e. glass-glass) alternative to air-glass micro-structuring. The principal advantage of the new approach is mechanical rigidity. A sufficiently large refractive index step between the component glasses exists to enable structures that rely on photonic bandgap effects for their operation to be realised in future work. Underpinning the development of these optical waveguides, the refractive index dispersion of bulk chalcogenide glasses As40Se60, Ge10As23.4Se66.6 and Ge17As18Se65 was measured using ellipsometry from 0.3 μm to 2.3 μm wavelength in this project. Also, the refractive index of thin As40Se60 films was measured and compared with that of bulk As40Se60 samples. Finally a Se precursor purification process was developed to enhance the purity of the end-glasses.

Item Type

ethesis

Thesis Type

PhD

Supervisors