Signal-to-noise ratio enhancement in frequency-modulation spectrometers by digital signal processing

Abstract

A signal-to-noise ratio enhancement of an order of magnitude was observed when digital signal-processing algorithms were applied to two diode-laser frequency-modulation spectrometers in the near-infrared and midinfrared spectral ranges. These algorithms include digital bandpass filters, a Wiener filter, a matched filter, and a least-squares fit. Digital signal processing has a practical advantage over other noise suppression techniques because it is easy to implement and to adapt to all experiment configurations without any physical modifications or additions to the spectrometer.