Nd-oscillator with fiber Q-switch

Industrial and scientific applications require lasers with high beam quality in Q-switched operation. In oscillators the high reflecting mirror can be substituted by a phase conjugating mirror based on stimulated Brillouin scattering (SBS). Due to the nonlinear response of such a mirror not only the beam quality can be improved also Q-switching can be obtained with the same element. Up to now toxic liquids or gases under high pressure were used as SBS-media in pulsed solid state oscillators. These media can be substituted by a simple multimode fiber. A pulsed oscillator with a multimode fiber inside was realized. Nd:YALO was used as active medium. The flashlamp duration is about 140 mu s and the threshold energy for laser operation is 5 J. The repetition rate can be varied from 1 Hz up to 25 Hz. The energy per shot is about 16 mi. Due to the relatively low SBS threshold a burst of Q-switched pulses per flashlamp shot occurs. The pulse width can be varied between 0.5 ns and 10 ns which depends on the used resonator configuration and the fiber.