Linear and nonlinear optical properties of the piezoelectric crystal α-GeO₂

We report the first measurements of phase-matching angles for second-harmonic generation, sum- and difference- frequency generations performed over the transparency range of the uniaxial α-GeO 2 crystal. A simultaneous fit of these data provided dispersion equations. The optical damage threshold and the magnitude of the nonlinear coefficient d 11 are also determined. We found | d 11 G e O 2 ( 0.67 μ m ) | = 0.76 ± 0.09 pm/V.