Generation of the optical second harmonic in noncommensurate phases of crystals
Aleksandrov K.S., Vtyurin A.N., Shabanov V.F.
Experimental investigations of the generation of the second harmonic have revealed an asymmetry in the nonlinear-susceptibility tensor of the noncommensurate phase of the (NH4)2BeF4 crystal. This effect is attributed to spatial modulation along the a axis.