Recent advancements in Differential Absorption Lidar (DIAL) technology have led to the adoption of fully fiber-optic DIAL systems, offering superior robustness, reduced alignment sensitivity, and enhanced portability compared to traditional bulk-optic systems. These systems excel in environmental monitoring, atmospheric research, and industrial safety. Central to their performance is the stabilization of the laser's frequency against environmental perturbations, crucial for pinpointing gas absorption peaks. This study introduces Wavelength Modulation Spectroscopy (WMS) for frequency stabilization in fully fiber-optic DIAL system, highlighting its simplicity and cost-effectiveness over conventional laser frequency-locking methods for applications where extreme precision is not mandatory. We present a compact, portable fiber-optic DIAL system designed for measuring CO2 concentrations with up to 10 ppm accuracy. The system ensuring laser wavelength stability below 140 MHz over several days, which contributes to the CO2 maximum absolute error detection of 0.5 ppm at narrow absorption peaks (half-width ~5 GHz).
Kikilich et al. (Thu,) studied this question.