Intra-cavity absorption sensor based on erbium-doped fiber laser

The sensitivity of power to relative cavity loss of the intra-cavity sensor based on erbium-doped fiber laser is investigated. Theoretical analysis and simulation show that the coupling ratio of coupler and the pump power have a great effect on sensitivity of ring intra-cavity sensor. And we have experimentally found that the sensitivity can be significantly enhanced as pump power approaches the threshold and the coupling ratio is higher.