Effect of optical activity on type-I and type-II phase matching in second-harmonic generation.

Optical activity changes the refractive indices of a crystal, and these changes should be taken into account when calculating the phase-matching angles. A method for calculating this change in refractive indices is presented and the effects on the phase-matching direction in KTiOPO(4) are shown. Although, in this case, the change is small, it may be considerably larger in other crystals.