WAVELENGTH INSENSITIVE PHASE-MATCHED 2ND-HARMONIC GENERATION IN PARTIALLY DEUTERATED KDP

We have experimentally determined the spectrally noncritical phase-matching behavior of type I frequency doubling in potassium dihydrogen phosphate (KDP) and its dependence on deuteration level in partially deuterated KD*P. Our results are in agreement with predictions based on available refractive-index data. The first-order wavelength-sensitivity parameter partial derivative-DELTA-k/partial derivative-lambda for type I doubling of 1.053-mu-m light vanishes for a KD*P crystal with a deuteration level of 12 +/- 2%. Calculations of this effect in other KDP analogs are presented, and the possibility of finding materials that have spectrally noncritical behavior for other phase-matched processes is discussed.