Mid-IR spectroscopy with NIR grating spectrometers

Abstract

Mid-infrared (mid-IR) spectroscopy is a crucial workhorse for a plethora of analytical applications and is suitable for diverse materials, including gases, polymers or biological tissue. However, this technologically significant wavelength regime between 2.5-10$\mu$m suffers from technical limitations primarily related to the large noise in mid-IR detectors and the complexity and cost of bright, broadband mid-IR light sources. Here, using highly non-degenerate, broadband photon pairs from bright spontaneous parametric down-conversion (SPDC) in a nonlinear interferometer, we circumvent these limitations and realise spectroscopy in the mid-IR using only a visible (VIS) solid-state laser and an off-the-shelf, commercial near-infrared (NIR) grating spectrometer. With this proof-of-concept implementation, covering a broad range from 3.2$\mu$m to 4.4$\mu$m, we access short integration times down to 1s and signal-to-noise ratios above 200 at a spectral resolution from 12cm${}^{-1}$ down to 1.5cm${}^{-1}$ for longer integration times. Through the analysis of polymer samples and the ambient CO${}_2$ in our laboratory, we highlight the potential of this measurement technique for real-world applications.

12 pages, 4 figures, submitted to Optics Express

References in corpus (7)

• Terahertz Quantum Sensing
• Hyperspectral Infrared Microscopy With Visible Light
• Nonlinear interferometer for Fourier-transform mid-infrared gas spectroscopy using near-infrared detection
• Fourier transform infrared spectroscopy with visible light
• Nonlinear infrared spectroscopy free from spectral selection
• Ultra-broadband SPDC for spectrally far separated photon pairs
• Biological Microscopy with Undetected Photons