title: A novel multipass scheme for enhancement of second harmonic generation.
abstract: We present experimental evidence of enhancement of the second-harmonic generation by using a multipass non-collinear phase-matching configuration for a Q-switched nanosecond-kilohertz Nd:YVO4 laser. In comparison with the single-pass configuration, the enhancement factor of the second-harmonic laser with the two-pass configuration is up to 2.5 in a type I beta-barium borate crystal, which can be further increased by adding the third-pass through the crystal. In addition, we provide a general relationship between the phase-matching angle and tilting azimuth angles of the unconverted fundamental and second-harmonic lasers. The multipass non-collinear phase-matching configuration is capable of reducing a thermal effect due to the absorption in the crystal and effectively avoiding damages on the crystal surfaces.
authors: Department of Mechanical Systems Engineering, Faculty of Engineering, University of Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan. harimoto@yamanashi.ac.jp
authors: Tetsuo
authors: T
authors: Harimoto
authors: Boku
authors: B
authors: Yo
authors: Kosuke
authors: K
authors: Uchida