Nonlinear interferometer for Fourier-transform mid-infrared gas spectroscopy using near-infrared detection

Abstract

Nonlinear interferometers allow for mid-infrared spectroscopy with near-infrared detection using correlated photons. Previous implementations have demonstrated a spectral resolution limited by spectrally selective detection. In our work, we demonstrate mid-infrared transmission spectroscopy in a nonlinear interferometer using single-pixel near-infrared detection and Fourier-transform analysis. A sub-wavenumber spectral resolution allows for rotational-lineresolving spectroscopy of gaseous samples in a spectral bandwidth of over 700 cm −1 . We use methane transmission spectra around 3.3 µm wavelength to characterize the spectral resolution, noise limitations and transmission accuracy of our device. The combination of nonlinear interferometry and Fourier-transform analysis paves the way towards performant and efficient mid-infrared spectroscopy with near-infrared detection.

Mid-IR spectroscopy with NIR grating spectrometers

“…For the task of spectroscopy, the initial proof of principle demonstration [11] has seen subsequent improvement [22], attaining a spectral resolution of 5 cm −1 across 120 cm −1 of bandwidth at 2200 nm, albeit with an impractical measurement time (with 30 s required for a single fringe). A direct FTIR analog has also been developed [23] and subsequently improved [24], realising a resolution and bandwidth of 0.56 cm −1 and 700 cm −1 respectively, with an acquisition time of 900 s. However, these FTIR implementations are effectively single-pixel approaches, and therefore do not fully exploit a central advantage of the 'sensing with undetected photons' paradigm: the use of the detection technologies otherwise absent at the sensing wavelength -in this case the availability of low-noise, fast ( >100 kHz) and cost-effective kilopixel sensor arrays.…”

Quantum metrology of two-photon absorption

“…Quantum-enhanced absorption measurements have received renewed attention recently [16][17][18][19][20][21][22][23][24] with the development of new quantum light sources and an increased interest in sensing technologies [25], as well as the demonstration of "sensing with undetected photons" [26][27][28][29][30]. Interest in this problem dates back to 2007, where the optimal estimation of single photon losses was first considered [31,32].…”

General simulation method for spontaneous parametric down- and parametric up-conversion experiments

“…Entangled and correlated photon pairs have become the basis for many applications in quantum optics. They are used in various quantum based schemes such as ghost imaging [1,2], optical coherence tomography [3], spectroscopy [4,5], quantum sensing [6], and imaging with undetected photons [7][8][9]. One of the most prominent methods for generating entangled photon pairs is spontaneous parametric down-conversion (SPDC), where a pump laser photon decays into two lower-energy photons in a medium with a second-order nonlinearity.…”