Investigation of erbium-doped fiber laser intra-cavity absorption sensor for gas detection

Steady state theoretical analysis of an erbium-doped fiber laser intra-cavity absorption sensor shows that high sensitivity can be achieved when the laser is working near threshold but is limited by the spontaneous emission. Experiments are carried out using a linear cavity fiber laser. The general trends of experimental results agree with the theoretical prediction. The use of the intra-cavity sensor for gas detection is demonstrated. A sensitivity of 91 times that of a single-pass absorption sensor is achieved.