A novel technique for characterizing effective second order nonlinearity in nonlinear crystals is presented. It utilizes group-velocity walk-off between femtosecond pulses in type-II SHG to achieve three-dimensional resolution of the effective nonlinearity. The longitudinal and transversal spatial resolution can be independently set. The technique is especially useful for characterizing quasi-phase-matched nonlinear crystals and it is demonstrated in PPKTP.

© 2003 Optical Society of America

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