Quantum Fourier-Transform Infrared Spectroscopy for Complex Transmittance Measurements

Harnessing the quantum interference of pair generation processes, infrared spectroscopy, based on nonlinear interferometers with visible-infrared photon-pair sources, enables extraction optical properties a sample through visible photon detection without need for an source or detector. We develop theoretical framework Fourier-transform (QFTIR) spectroscopy. The proposed Fourier analysis method, which fully utilizes phase information in interferogram, allows us to determine complex transmittance and constants simple setup use any dispersive optics spectral selection. In experimental demonstrations, spectrum bandpass filter refractive index silica glass are measured near-infrared region using QFTIR operated low gain regime; these results agree well independently conventional spectrometer value estimated from references. These demonstrations prove validity great potential