Cryoless MIR spectroscopy via pump wavelength scanning using PPLN ridge waveguide upconversion

This article presents what we believe to be a novel room-temperature mid-wave Infrared spectroscopy (MWIR) technique utilizing upconversion in a 2 cm-long PPLN ridge waveguide. Addressing limitations of costly, cryo-dependent FTIR, our "non-linear spectrometer" samples MWIR spectra by sweeping a low-power, continuous wave monochromatic pump laser, enabling detection with sensitive silicon detectors. Experimental validation with a channelled spectrum demonstrated accurate thermal source spectral modulation recovery, showing a 3% relative error. This robust approach offers a promising pathway for miniaturized, practical MIR spectroscopic tools.