Surface plasmon polariton boosted photorefractive scattering in indium tin oxide coated Fe-doped lithium niobate slabs

To study the impact of surface plasmon polaritons on photorefractive effect, indium tin oxide (ITO) thin films were deposited onto Fe-doped lithium niobate (Fe: LiNbO3, LN) slabs. Striking scattering near surface normal (SNSN) of the slabs was observed, increasing with the incident angle of laser beam. The SNSN was so strong that it depleted the transmitted beam. Based on a tentative physical picture of photovoltaic (PV) effect induced electrostatic modification, the electron density of skin layer of ITO film was raised to such a level that surface plasmon polaritons (SPPs) were excited in LN/ITO interface via phase grating mediation. Consequently, the localized intensified electromagnetic fields exerted on the LN slabs and resulted in the SNSN. The impact of the SPPs and SNSN on the photorefractive effect can be seen from over 2.5 times SNSN enhancement in power and as high as 6.0 times boosting of the ratio of the SNSN power to the remaining transmitted one.