First experimental demonstration of an all-fiber ring laser in the 2 μm regime that is tunable under loss variation (covering absorption of water peak and green-house gases); continuously tunable laser can be used for (i) Multiple gas detection (ii) High discrimination between gases.

The numerical model for ring laser successfully predicts the parameters useful in the choice of the length and operation regime for the experiment.

Optimal length in the present configuration for narrow linewidth is greater than the optimal length for maximum power reported earlier.

Narrow linewidth emission that is comparable to that using an FBG/filter has been demonstrated.