Simulations and experiments on resonantly-pumped single-frequency Erbium lasers at 1.6 μm

We report on a single-frequency laser oscillator based on a new Er:YLuAG laser crystal which is spectrally suitable for application as a transmitter in differential absorption lidar measurements of atmospheric CH₄. The laser emits single-frequency laser pulses with 2.3 mJ of energy and 90 ns duration at a repetition rate of 100 Hz. It is resonantly pumped by two linearly polarized single-mode cw fiber lasers at 1532 nm. A scan of the CH ₄-absorption line at 1645.1 nm was performed and the shape of the line with its substructure was reproduced as theoretically predicted. A 2.5-dimensional performance model was developed, in which pump absorption saturation and laser reabsorption is included. Also the spectral output of the laser oscillator longitudinal multimode operation could be predicted by the laser model.