Broadband mid-infrared cavity ringdown spectroscopy with frequency upconversion detector

Detection of mid-infrared light (λ in range of 2-5 μm) is traditionally limited by noisy and slow detectors. Upconversion of infrared light to near-infrared wavelengths enables fast and sensitive mid-infrared (MIR) detection using regular Si detectors or photomultiplier tubes (PMT). Efficient continuous wave (CW) upconversion has been introduced in spectral imaging [1] and spectrometer applications [2]. We apply upconversion to cavity ringdown spectroscopy CRDS by using a pulsed supercontinuum light source at 3 μm wavelength region. Intracavity upconversion utilizes sum frequency generation (SFG) between 1064 nm Nd:YVO
₄
laser field and MIR wavelengths resulting detection at 780 nm region.