Development of an eye-safe solid-state tunable laser transmitter in the 1.4-1.5 microm wavelength region based on Cr4+:YAG crystal for lidar applications.

An experimental optimization of the efficiency of a gain switched tunable Cr4+:YAG laser at 10 Hz is described. The thermal lensing during pulsed operation was measured. Optimal performance occurred at a crystal temperature of 34 degrees C and resulted in an output energy of approximately 7 mJ and a pulse duration of approximately 35 ns. Tunability in the range of 1350-1500 nm, spectral linewidth of approximately 200 GHz, and M2<4 are demonstrated. The main laser material parameters are estimated. Such a laser could be employed in a laboratory-based nonscanning lidar system if a narrowband birefringent filter is installed. The tunability will permit the improvement of the Cr4+:YAG transmitter for water-vapor differential absorption lidar if injection seeding is applied.