Spectroscopy and Imaging Using a Mid-IR Quantum Cascade Optical Coherence Tomography (OCT) System

Varnell, Deborah; Mei, Zhigang; Chow, Martin; Gmachl, Claire F.

doi:10.1364/cleo_at.2016.atu1j.7

Cited by 4 publications

(1 citation statement)

References 2 publications

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“…[92][93][94] Further, an optical coherence tomography (OCT) system in the mid-IR region based on a QCL has been realized. 95,96 The improved characteristics of QCLs enabled the implementation of frequency combs 97 that provide an emission spectrum composed of a set of modes that are perfectly equally-spaced and have a well-defined phase relationship between each other. 98,99 In molecular spectroscopy, these optical sources have been employed for dual-comb spectroscopy that is based on the generation of a multi-heterodyne beating between two frequency combs with slightly different repetition frequencies.…”

Section: Specific Properties Of Qcls Relevant For Applied Spectroscopymentioning

confidence: 99%

Quantum cascade lasers (QCLs) in biomedical spectroscopy

2017

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Quantum cascade lasers (QCL) are the first room temperature semiconductor laser source for the mid-IR spectral region, triggering substantial development for the advancement of mid-IR spectroscopy. Mid-IR spectroscopy in general provides rapid, label-free and objective analysis, particularly important in the field of biomedical analysis. Due to their unique properties, QCLs offer new possibilities for development of analytical methods to enable quantification of clinically relevant concentration levels and to support medical diagnostics. Compared to FTIR spectroscopy, novel and elaborated measurement techniques can be implemented that allow miniaturized and portable instrumentation. This review illustrates the characteristics of QCLs with a particular focus on their benefits for biomedical analysis. Recent applications of QCL-based spectroscopy for analysis of a variety of clinically relevant samples including breath, urine, blood, interstitial fluid, and biopsy samples are summarized. Further potential for technical advancements is discussed in combination with future prospects for employment of QCL-based devices in routine and point-of-care diagnostics.

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Section: Specific Properties Of Qcls Relevant For Applied Spectroscopymentioning

confidence: 99%

Quantum cascade lasers (QCLs) in biomedical spectroscopy

2017

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Real-time high-resolution mid-infrared optical coherence tomography

et al. 2019

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The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s. Nevertheless, the development of mid-infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region, resulting in slow acquisition, low sensitivity, and poor axial resolution. In this work, a mid-infrared spectral-domain optical coherence tomography system operating at a central wavelength of 4 µm and an axial resolution of 8.6 µm is demonstrated. The system produces two-dimensional cross-sectional images in real time enabled by a high-brightness 0.9- to 4.7-µm mid-infrared supercontinuum source with a pulse repetition rate of 1 MHz for illumination and broadband upconversion of more than 1-µm bandwidth from 3.58–4.63 µm to 820–865 nm, where a standard 800-nm spectrometer can be used for fast detection. The images produced by the mid-infrared system are compared with those delivered by a state-of-the-art ultra-high-resolution near-infrared optical coherence tomography system operating at 1.3 μm, and the potential applications and samples suited for this technology are discussed. In doing so, the first practical mid-infrared optical coherence tomography system is demonstrated, with immediate applications in real-time non-destructive testing for the inspection of defects and thickness measurements in samples that exhibit strong scattering at shorter wavelengths.

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