Optimal design for wavelength conversion with a configuration of walk-off compensation in free space in the nanosecond pulsed regime.

On the basis of standard wavelength conversion by the use of angular phase matching of nonlinear optical crystals arranged in free space, applicable to a wide range of wavelengths and laser intensities, we both numerically and experimentally present an optimal design for achieving near-full energy conversion while maintaining good TEM mode property of fundamental laser radiation in the nanosecond regime.