Share Email Print

Proceedings Paper

The mid-infrared swept laser: life beyond OCT?
Author(s): D. T. D. Childs; R. A. Hogg; D. G. Revin; Ihtesham U. Rehman; J. W. Cockburn; S. J. Matcher
Format Member Price Non-Member Price
PDF $17.00 $21.00

Paper Abstract

Near-infrared external cavity lasers with high tuning rates (“swept lasers”) have come to dominate the field of nearinfrared low-coherence imaging of biological tissues. Compared with time-domain OCT, swept-source OCT a) replaces slow mechanical scanning of a bulky reference mirror with much faster tuning of a laser cavity filter element and b) provides a ×N (N being the number of axial pixels per A-scan) speed advantage with no loss of SNR. We will argue that this striking speed advantage has not yet been fully exploited within biophotonics but will next make its effects felt in the mid-infrared. This transformation is likely to be driven by recent advances in external cavity quantum cascade lasers, which are the mid-IR counterpart to the OCT swept-source. These mid-IR sources are rapidly emerging in the area of infrared spectroscopy. By noting a direct analogy between time-domain OCT and Fourier Transform Infrared (FTIR) spectroscopy we show analytically and via simulations that the mid-IR swept laser can acquire an infrared spectrum ×N (N being the number of spectral data points) faster than an FTIR instrument, using identical detected flux levels and identical receiver noise. A prototype external cavity mid-IR swept laser is demonstrated, offering a comparatively low sweep rate of 400 Hz over 60 cm-1 with 2 cm-1 linewidth, but which provides evidence that sweep rates of over a 100 kHz should be readily achievable simply by speeding up the cavity tuning element. Translating the knowledge and experience gained in near-IR OCT into mid-IR source development may result in sources offering significant benefits in certain spectroscopic applications.

Paper Details

Date Published: 2 March 2015
PDF: 4 pages
Proc. SPIE 9312, Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIX, 931239 (2 March 2015); doi: 10.1117/12.2081872
Show Author Affiliations
D. T. D. Childs, The Univ. of Sheffield (United Kingdom)
R. A. Hogg, The Univ. of Sheffield (United Kingdom)
D. G. Revin, The Univ. of Sheffield (United Kingdom)
Ihtesham U. Rehman, The Univ. of Sheffield (United Kingdom)
J. W. Cockburn, The Univ. of Sheffield (United Kingdom)
S. J. Matcher, The Univ. of Sheffield (United Kingdom)

Published in SPIE Proceedings Vol. 9312:
Optical Coherence Tomography and Coherence Domain Optical Methods in Biomedicine XIX
James G. Fujimoto; Joseph A. Izatt; Valery V. Tuchin, Editor(s)

© SPIE. Terms of Use
Back to Top
Sign in to read the full article
Create a free SPIE account to get access to
premium articles and original research
Forgot your username?