A multipass configuration for second-harmonic generation of Nd:YAG laser radiation is demonstrated to produce, for the first time to the authors’ knowledge in twin lithium tetraborate crystals, as much as 21% conversion efficiency even though the effective nonlinear coefficient of the crystal is as low as 1/6th that of KDP. Apart from crystals that have large walk-off angles, low effective nonlinear coefficients, or both, the simple experimental setup would also be quite suitable for those crystals, especially infrared crystals, that have large effective nonlinear coefficients but low laser damage thresholds.
© 2005 Optical Society of America
Original Manuscript: June 23, 2004
Revised Manuscript: October 22, 2004
Manuscript Accepted: October 29, 2004
Published: February 10, 2005
Udit Chatterjee, Sudipta Gangopadhyay, Chittaranjan Ghosh, and Gopal C. Bhar, "Multipass configuration to achieve high-frequency conversion in Li2B4O7 crystals," Appl. Opt. 44, 817-821 (2005)