Modified chalcogenide glasses for optical device applications

Hughes, MA

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.
Vanadium doped GLS displays three absorption bands at 580, 730 and 1155 nm
identified by photoluminescence excitation measurements. Broad photoluminescence,
with a full width half maximum of ~500 nm, is observed peaking at 1500 nm when
exciting at 514, 808 and 1064 nm. The fluorescence lifetime and quantum efficiency at
300 K were measured to be 33.4 μs and 4% respectively. Analysis of the emission
decay, at various vanadium concentrations, indicated a preferentially filled, high
efficiency, oxide site that gives rise to characteristic long lifetimes and a low efficiency
sulphide site that gives rise to characteristic short lifetimes. X-ray photoelectron
spectroscopy measurements indicated the presence of vanadium in a broad range of
oxidation states from V+ to V5+. Tanabe-Sugano analysis indicates that the optically
active ion is V2+ in octahedral coordination and the crystal field strength (Dq/B) was
1.84. Titanium and nickel doped GLS display a single absorption band at 590 and 690
nm, and emission lifetimes of 97 and 70 μs respectively. Bismuth doped GLS displays
two absorption bands at 665 and 850 nm and lifetime components of 7 and 47 μs. Based
on comparisons to other work the optically active ions are proposed to be Ti3+, Ni+ and
Bi+, all of these displayed emission peaking at ~900 nm.
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 wave

Citation

Hughes, M. (in press). Modified chalcogenide glasses for optical device applications. (Thesis). University of Southampton

• Thesis Type: Thesis
• Acceptance Date: Mar 19, 2023
• Deposit Date: Jun 5, 2017
• Publicly Available Date: Jun 5, 2017
• Publisher URL: https://eprints.soton.ac.uk/47761/
• Related Public URLs: https://eprints.soton.ac.uk/47761/
• Additional Information: Funders : Engineering and Physical Sciences Research Council (EPSRC)
• Award Date: May 1, 2007