Vacuum partial pressure measurement using low-budget dual comb system

Dual-comb spectroscopy is a powerful tool for gas sensing but its expensive cost is limiting its practical application in many fields. In terms of this issue, we present a low-cost and effective dual-comb generation method without complicated feedback lock electronics and nonlinear optics. The proposed dual combs are seeded with the same CW laser, and modulated by electric-optic modulators driven by a pair of pulse trains with slightly different repetition rates of 200 MHz and 200.25 MHz to generate tooth resolved spectrum. A pair of vacuum partial pressure measurements were performed to demonstrate its feasibility and ability. In the experiment, the built dual-comb apparatus is applied to analyze two standard gas mixtures containing carbon monoxide and carbon dioxide respectively. The relative deviations of measurement results against their certified values for carbon monoxide and carbon dioxide are both below 2%. Furthermore, by averaging a set of measurement results at different wavenumbers, the deviation could further be reduced, indicating that the proposed manner is capable of enabling gas partial pressure measurement with good accuracy and low cost.