# Quantum dot superluminescent diodes for optical coherence tomography: Device engineering

Purnima D L Greenwood, David T D Childs, Kenneth Kennedy, Kristian M. Groom, Maxime Hugues, Mark Hopkinson, Richard A. Hogg, Nikola Krstajić, Louise E. Smith, Stephen J. Matcher, Marco Bonesi, Sheila MacNeil, Rod Smallwood

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)

## Abstract

We present a 18 mW fiber-coupled single-mode superluminescent diode with 85 nm bandwidth for application in optical coherence tomography (OCT). First, we describe the effect of quantum dot (QD) growth temperature on optical spectrum and gain, highlighting the need for the optimization of epitaxy for broadband applications. Then, by incorporating this improved material into a multicontact device, we show how bandwidth and power can be controlled. We then go on to show how the spectral shape influences the autocorrelation function, which exhibits a coherence length of <11 $\mu$m, and relative noise is found to be 10 dB lower than that of a thermal source. Finally, we apply the optimum device to OCT of in vivo skin and show the improvement that can be made with higher power, wider bandwidth, and lower noise, respectively.

Original language English 5445054 1015-1022 8 IEEE Journal on Selected Topics in Quantum Electronics 16 4 https://doi.org/10.1109/JSTQE.2009.2038720 Published - Jul 2010

## Keywords

• Optical coherence tomography (OCT)
• quantum dot (QD)
• skin imaging
• superluminescent diodes (SLEDs)