Sensitivity-enhanced intracavity-absorption acetylene sensor based on mode competition

We propose and demonstrate a sensitivity-enhanced intracavity-absorption gas sensor based on the phenomenon of mode competition in the dual-wavelength ring fiber laser theoretically and experimentally. The laser configuration possesses the sensing and reference wavelengths as 1530.372 nm and 1532.168 nm, respectively. When the 2-meter-long hollow-core photonic crystal fiber (HC-PCF) is filled with 1000-ppmv acetylene, a sudden decrease on sensing wavelength intensity of 38.6 dB can be achieved, resulting from the mode competition between the sensing and reference wavelengths. The minimum detectable acetylene concentration (MDAC) of 29.53 ppmv is obtained in our experiment, one order of magnitude higher than former works.