Laser with diffraction-limited divergence and Q switching by stimulated Brillouin scattering

A laser is described utilizing neodymium phosphate glass, an unstable resonator, and Q switching by stimulated Brillouin scattering. It was found that Q switching occurred when the resonator changed over from an unstable to a stable configuration. Wavefront reversal then caused lasing to take place in the lowestorder mode, the radiation having the diffraction-limited divergence and completely filling the 6.3 mm diameter of the active element.