Photonic devices for integrated optical applications
Psaila, Nicholas David
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work presented in this thesis encompasses an investigation into the use of ultrafast laser inscription in the fabrication of glass based photonic devices for integrated optical applications. Waveguide fabrication and characterisation experiments were carried out in three categories of glass substrate. Firstly, waveguides were inscribed in an erbium doped glass with the aim of fabricating optical amplifiers and lasers operating in the 1.5 μm spectral region. Low loss waveguides were fabricated in substrates with different dopant concentrations. Fibre to fibre net gain was achieved from one substrate composition, however it was found that ion clustering limited the amount of achievable gain. Laser action was demonstrated by constructing an optical fibre based cavity around the erbium doped waveguide amplifier. Waveguides were also inscribed in bismuth doped glass with the aim of fabricating optical amplifiers and lasers operating in the 1.3 μm spectral region. Low loss waveguides were fabricated, however the initial composition was incapable of providing gain. A proven substrate material was employed, demonstrating ultra-broadband gain spanning more than 250 nm. High losses prevented the achievement of net gain, however the broad potential of the substrate material was highlighted. Finally, waveguides were inscribed in a Chalcogenide glass. Strong refractive index contrasts were observed, with a wide range of waveguiding structures produced. Supercontinuum experiments were carried out in order to confirm the nonlinear behaviour of the waveguides. A spectrally smooth supercontinuum spanning 600 nm was generated, providing a potentially useful source for optical coherence tomography.