A Firefly Algorithm-Based Spectral Fitting Technique for Wavelength Modulation Spectroscopy Systems

This article proposes a novel calibration-free wavelength modulation spectroscopy (WMS) spectral fitting technique based on the firefly algorithm (FA). The technique simulates the behavior of information interaction between fireflies to accurately retrieve gas concentrations and laser parameters. Compared to the spectral fitting technique based on the classical Levenberg–Marquardt (LM) algorithm, the proposed technique exhibits weak dependence on the precharacterization of laser tuning parameters during gas concentration retrieval. We select the P(13) absorption line of
$\text{C}_{{2}}\text{H}_{{2}}$
at 1532.82 nm as the target spectra and compare the performance of two optimization methods (LM and firefly) on gas concentration and laser tuning parameters retrieval by simulation. The simulation results demonstrate that the FA-based spectral fitting technique exhibits superior performance in terms of both convergence speed and fitting accuracy for multiparameter models without exact characterization.