Intracavity absorption gas sensor in the near-infrared region by using a tunable erbium-doped fiber laser based on a Hi-Bi FOLM

We report an experimental study erbium-doped fiber laser for gas pressure detection in the L-band wavelength region by laser intracavity absorption spectroscopy. By using a high-birefringence fiber optical loop mirror as spectral filter within the ring cavity laser, the wavelength of the generated laser line is finely selected and tuned in a range of 10 nm in order to select the wavelength where the gas absorption line is exhibited. Experimental results for detection of CO₂ pressure with absorption at 1573.2 nm are shown and discussed. The proposed fiber laser sensor exhibits reliability and stability for gas detection with absorption in the L-band such as CO₂, CO, and H₂S.