Gallium Nitride Light Sources for Optical Coherence Tomography

Goldberg, G. R., Ivanov, P., Ozaki, N., Childs, D. T.D., Groom, K. M., Kennedy, K. L. and Hogg, R. A. (2017) Gallium Nitride Light Sources for Optical Coherence Tomography. In: Gallium Nitride Materials and Devices XII, San Francisco, CA, USA, 30 Jan - 02 Feb 2017, 101041X. ISBN 9781510606494 (doi:10.1117/12.2252665)

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Abstract

The advent of optical coherence tomography (OCT) has permitted high-resolution, non-invasive, in vivo imaging of the eye, skin and other biological tissue. The axial resolution is limited by source bandwidth and central wavelength. With the growing demand for short wavelength imaging, super-continuum sources and non-linear fibre-based light sources have been demonstrated in tissue imaging applications exploiting the near-UV and visible spectrum. Whilst the potential has been identified of using gallium nitride devices due to relative maturity of laser technology, there have been limited reports on using such low cost, robust devices in imaging systems. A GaN super-luminescent light emitting diode (SLED) was first reported in 2009, using tilted facets to suppress lasing, with the focus since on high power, low speckle and relatively low bandwidth applications. In this paper we discuss a method of producing a GaN based broadband source, including a passive absorber to suppress lasing. The merits of this passive absorber are then discussed with regards to broad-bandwidth applications, rather than power applications. For the first time in GaN devices, the performance of the light sources developed are assessed though the point spread function (PSF) (which describes an imaging systems response to a point source), calculated from the emission spectra. We show a sub-7μm resolution is possible without the use of special epitaxial techniques, ultimately outlining the suitability of these short wavelength, broadband, GaN devices for use in OCT applications

Item Type:Conference Proceedings
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ivanov, Dr Pavlo and Childs, Dr David and Hogg, Professor Richard and Goldberg, Graham
Authors: Goldberg, G. R., Ivanov, P., Ozaki, N., Childs, D. T.D., Groom, K. M., Kennedy, K. L., and Hogg, R. A.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
ISSN:0277-786X
ISBN:9781510606494
Copyright Holders:Copyright © 2017 Society of Photo-Optical Instrumentation Engineers
First Published:First published in Gallium Nitride Materials and Devices XII: 101041X
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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