Stable Intracavity Frequency Up-Conversion for Mid-Infrared Spectroscopy

Up-conversion-based spectrometers are powerful tools for mid-infrared spectroscopy, especially in applications requiring high acquisition rates [1]. The traditional instruments used in the mid-infrared domain are Fourier transform spectrometers; however, they are limited by their low sampling rate (~ 1 Hz) and high thermal noise if not cryogenically cooled. The usage of a non-linear frequency up-conversion is an alternative approach, which allows one to translate an infrared signal into the near-visible domain, where fast and sensitive silicon-based sensors are available [2]. This eliminates the need for cryocooling systems and allows for broad-band MIR spectroscopy with a kilohertz sampling rate.