High-order diffraction and nanolayer electrostatic modification in Cu-doped (K_05Na_05)_02(Sr_075Ba_025)_09Nb_2O_6 crystals

Abstract

Electrostrictive and photoinduced charge accumulation in the nanoscale interfaces of air and copper-doped (K0.5Na0.5)0.2(Sr0.75Ba0.25)0.9Nb2O6 crystals and electrostatic modification to the nanolayer interfaces were studied with conventional two beam coupling. This interface modification was confirmed by (1) emerging 2 dimensional diffraction patterns with over 10 high orders and 6 rows; (2) remarkable electroinduced power change of specular reflection on the very first surface; and (3) the energy coupling of the first reflected beam with another coherent laser beam in the subwavelength scale. Distinct responses to perturbation show coexistence of a surface grating and bulk ones in the sample. Theoretical consideration on excitation of surface plasmon polaritons through photorefractive phase grating mediation was given to elucidate all the related observations.