Supercontinuum (SC) light source is certainly one of the best option for ultra-high resolution optical coherence tomography (UHR-OCT). Over the last few years several demonstrations have been done for each commonly used wavelength range [1-2-3]. Nowadays, SC dedicated to UHR-OCT is a mature technology with turn-key commercially available system . The new challenge to answer for SC source is the cost reduction one.
In this study, we demonstrate that a Q-switched based SC (QS-SC) could be an alternative to the current state of the art SC based on a Mode-Locked laser (ML-SC). This QS-SC, whose cost is less than 15 % of the ML-SC, offers similar possibilities in terms of bandwidth, beam quality and optical density within the OCT band . We demonstrate the usefulness of such a source by direct comparison with the ML-SC source commonly used. Our study includes a comparison of the pulse to pulse stability of both sources over the OCT wavelength range, where it is shown that the QS-SC is much more stable than the ML-SC. Also, a noise analysis conducted from the OCT point of view shows that the source repetition rate is a key parameter for any SC based OCT system. A comparison of images acquired from biological and non-biological samples is performed with emphasis on their contrast. Our conclusion is that a QS-SC can be used a useful source for UHR-OCT if compromise can be done in terms of speed of the detection unit. Finally, our study has been done at a central wavelength of 1270 nm, however the ultra-broad flat spectrum of the QS-SC makes it an interesting source for the 800 nm or visible range OCT too, opening the door for low-cost multi-band or multi-modal OCT.
1. K. Bizheva, B. Tan, B. MacLelan, O. Kralj, M. Hajialamdari, D. Hileeto, and L. Sorbara, “Sub-micrometer axial resolution OCT for in-vivo imaging of the cellular structure of healthy and keratoconic human corneas,” Biomed. Opt. Express 8, 800-812 (2017).
2. W. Yuan, J. Mavadia-Shukla, J. Xi, W. Liang, X. Yu, S. Yu, and X. Li, "Optimal operational conditions for supercontinuum-based ultrahigh-resolution endoscopic OCT imaging," Opt. Lett. 41, 250-253 (2016).
3. C. Cheung, J. Daniel, M. Tokurakawa, W. Clarkson, and H. Liang, "High resolution Fourier domain optical coherence tomography in the 2 μm wavelength range using a broadband supercontinuum source," Opt. Express 23, 1992-2001 (2015).