Improving Resolution of Dual-Comb Gas Detection Using Periodic Spectrum Alignment Method

Abstract

Dual-comb spectroscopy has been an infusive spectroscopic tool for gas detection due to its high resolution, high sensitivity, and fast acquisition speed over a broad spectral range without any mechanical scanning components. However, the complexity and cost of high-performance dual-comb spectroscopy are still high for field-deployed applications. To solve this problem, we propose a simple frequency domain post-processing method by extracting the accurate position of a specific absorption line frame by frame. After aligning real-time spectra and averaging for one second, the absorbance spectrum of H13C14N gas in the near-infrared is obtained over 1.1 THz spectral range. By using this method, the standard deviation of residual error is only ~0.002, showing great agreement with the conventional correction method. In addition, the spectral resolution is improved from 13.4 GHz to 4.3 GHz compared to direct spectrum averaging. Our method does not require a specially designed common-mode suppression comb, rigorous frequency control system, or complicated computational algorithm, providing a cost-effective scheme for field-deployed Doppler-limited spectroscopy applications.

Highly integrated repetition frequency locking control system for optical frequency comb

“…Based on the time domain and frequency domain characteristics of the optical frequency comb itself, the application of the optical frequency comb has two main aspects. One is to provide a stable frequency reference, and the other is to serve as a high-precision light source in precision measurement [2][3][4][5][6]. Free-running optical frequency combs have large repetition frequency fluctuations under the interference of various noises, and cannot be directly used for various precise measurements.…”

Broadband EOM frequency combs generation based on integrated silicon nitride waveguide

“…OFC is one kind of coherent light source composed of a set of discrete frequency lines that were equally spaced forming a comb picture and the spacing frequency is usually in the radio-frequency (RF) domain 1 . Previous research has shown that OFC has great applications in microwave signal processing 2 , high-performance waveform synthesis 3 , coherent optical communication 4 , and gas detection 5 . In general, there are different setups for OFC generation such as ones based on mode-locked femtosecond lasers, resonators, or EOMs.…”

A 209 MHz compact all-fiber Er-doped mode-locked laser

“…Typically, the NPR mode-locked fiber lasers include spatial light path part for polarization control and length adjustment [14][15][16][17][18], which puts forward strict requirement on precise collimation. Hence, this kind of laser can be easily interfered by environment.…”