Nonlinear interferometers for Fourier-transform infrared spectroscopy with visible light

Abstract

Nonlinear interferometers based on non-degenerate spontaneous parametric down-conversion (SPDC) create a link between separate spectral ranges. This allows for measurements in remote spectral regions while detecting light in easily accessible wavelengths. In our work, we use periodically poled lithium niobate to create correlated signal (visible or near-infrared) and idler (mid-infrared) photon pairs. Using a nonlinear interferometer in Michelson geometry, we obtain broadband mid-infrared spectra from light detected with a silicon avalanche photodiode. Combining the nonlinear interferometer with a measurement scheme in close analogy to classical Fourier-transform infrared spectroscopy allows for sub-wavenumber spectral resolution, which opens up possibilities for applications such as precise spectroscopic gas analysis.

Remote quantum ghost imaging

“…This broad overall emission is a result of the only small phase mismatch between different wavelengths, allowing the momentum conservation to "compensate" the mismatch. It further leads to a relation between the emission angle and wavelength of the photons [7]. By ensuring uniform momentum of all pump photons, the momentum correlation of the photon pairs (in other words their emission angle) becomes unambiguous.…”