Eye-Safe KGd(WO4)2:Nd Laser: Nano- and Subnanosecond Pulse Generation in Self-Frequency Raman Conversion Mode with Active Q-Switching

The shape of the multimode Stokes pulse generated by an eye-safe KGd(WO4)2:Nd laser with self-frequency Raman conversion and active Q-switching was shown to depend on the inhomogeneity of the active-medium pump. The laser generated a short and undistorted Stokes pulse of length ~2.5 ns that increased with increasing laser cavity length for a moderately inhomogeneous pump characterized by a higher population inversion in the center of the active element. The energy of the Stokes pulse (~11.5 mJ) varied little as the output-mirror reflectivity varied in the range 5–45%. The Raman pulse became distorted if the inhomogeneity of the pump was increased considerably. The degree of pump inhomogeneity was negligible with fundamental TEM00 mode selection. The laser generated subnanosecond Stokes pulses with peak power in the MW range.