Direct UV-written Bragg gratings for waveguide characterisation and advanced applications

Abstract

Direct UV writing is an established fabrication technique allowing channel waveguides and photonic circuits to be defined in a photosensitive glass via an inscription method. A related technique, direct grating writing, enables Bragg grating structures to be defined in an interferometric dual beam set up, with definition of Bragg grating planes achieved via the periodic modulation of the interference pattern between the beams. A decade of prior work investigating the technique has led to devices for use in sensing, telecommunications, lasing and amplification applications. A requirement for greater understanding of the propagation characteristics of the waveguides has been identified, in order to maximise the efficiency and effectiveness of these devices.

In this thesis, a propagation loss measurement technique and a wavelength-dependent dispersion measurement technique are presented. Both depend on the presence of integrated Bragg grating structures which enable the propagation characteristics of the waveguides to be investigated. The loss measurement technique involves measurement of the Bragg grating strength, whilst the dispersion measurement technique enables the effective refractive index of the waveguide to be inferred from a measurement of reflected central grating wavelength. Applications of both techniques in a variety of situations have been investigated, with devices fabricated for use in quantum technologies and cold matter experiments amongst those produced.

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Identifiers

ORCID for P.G.R. Smith: orcid.org/0000-0003-0319-718X

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