Passively Q switched laser with single longitudinal mode based on the frequency

A passively Q-switched side-pumped laser with folded resonator is specially constructed for singlelongitudinal-mode smooth pulse output. Nd:YAG is chosen as the laser active medium and Cr⁴⁺:YAG as the saturable absorber medium. Additionally, the method of frequency selection by grating with 1200 line/mm and Fabry-Perot (F-P) etalon is used in the twisted-mode cavity. The single-frequency smooth pulses are produced with 10-Hz repetition rate, 20-ns pulse width, and 1.064-\m