Peculiarities of Forming Single-Frequency Generation in a Monopulse YAG:Nd-Laser with Transverse Diode Pumping and Injection of Narrow-Band Radiation.

The features of forming output radiation in a powerful monopulse single-frequency side diode-pumped laser operating in external narrow-band signal seeding mode were investigated. The monopulse single-frequency laser was fabricated of a YAG:Nd active element excited by three laser diode matrices. A compact continuous-wave YAG:Nd-laser with longitudinal diode pumping served as the seeding laser. It was shown experimentally that the transition of the monopulse laser from multimode to single-frequency lasing with a spectral line width of about 54 MHz (0.2 pm) occurs at seeding-laser radiation power P ≈ 0.14 mW (radiation intensity of 1.8·10 W/cm). Increasing the seeding-laser power over P does not lead to a noticeable change of the output characteristics of the monopulse laser for a given pump level (above the threshold). If the pump power varies from 1.5 to 3.0 kW, the P value is not changed but the energy of the output pulses of single-frequency monopulse generation increases to 40 MJ. The low level of the external narrow-band seeding signal allows us to consider the single-frequency low-power semiconductor laser as a promising source of the seeding signal. [ABSTRACT FROM AUTHOR]