Modified chalcogenide glasses for optical device applications

Abstract

This thesis focuses on two different, but complementary, aspects of the modification of gallium lanthanum sulphide (GLS) glasses. Firstly the addition of transition metal ions as dopants is examined and their potential for use as active optical materials is explored. It is also argued that the spectroscopic analysis of transition metal ions is a useful tool for evaluating the local environment of their host. Secondly femtosecond (fs) laser modification of GLS is investigated as a method for waveguide formation. Through optical characterisation of fs laser written waveguides in GLS, a formation mechanism has been proposed. Tunnelling has been identified as the dominant nonlinear absorption mechanism in the formation of the waveguides. Single mode guidance at 633 nm has been demonstrated. The writing parameters for the minimum propagation loss of 1.47 dB/cm are 0.36 µJ pulse energy and 50 µm/s scanning speed. The observation of spectral broadening in these waveguides indicates that they may have applications for nonlinear optical devices. Fs laser written waveguides in transition metal doped GLS could lead to broadband active optical devices.

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ORCID for Daniel Hewak: orcid.org/0000-0002-2093-5773

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