Dual-point automatic switching intracavity-absorption photonic crystal fiber gas sensor based on mode competition

- The automatic switching intracavity acetylene sensor is demonstrated firstly via Sagnac loop filter (SLF).
- The sensitivities are 398 ppmV and 1905 ppmV at 1532.83 nm and 1534.10 nm, respectively. The resolution error is no more than 7.2 percent of the sensitivities.
- The tunable SLF provides an approach for intracavity hybrid gas sensor network.
- The detection speed is optimized by employing gradient voltage to tunable filter.

Here we propose a dual-point channel-switchable intracavity absorption hollow-core photonic crystal fiber acetylene sensing system based on the mode-competition phenomenon in a ring fiber laser with a Sagnac loop filter. The experimental system operating at 1532.83 and 1534.10 nm is applied to 1% acetylene and shows the sensitivities of 398 and 1905 ppmv, respectively, at the absorption peaks around two operating wavelengths. The resolution error induced by the power fluctuation is no more than 7.2% for both gas cells and it takes ∼50 s to scan the absorption spectra via applying gradient voltage to the tunable F-P filter. This approach is a potential cost-effective resolution for high-capacity intracavity absorption sensor network compatible hybrid gas detection.