Spontaneous and electric field induced quadratic optical nonlinearity in ferroelectric crystals AgNa(NO2)2

摘要

We demonstrate the second harmonic generation u0001SHGu0002 in ferroelectric AgNau0001NO2u00022 crystalsnresulting from the spontaneous and electric field induced polarizations. Relatively high effectivennonlinear optic u0001NLOu0002 susceptibility is combined in this crystals with the existing several phasenmatching geometries of NLO interaction. Anomalously large response of SHG with respect to annapplied electric field has been found in the vicinity of the paraelectric-to-ferroelectric phasentransition. The behavior of NLO properties in the ferroelectric phase and especially in the region ofnthe Curie point is discussed within the phenomenological theory.