La-doped PMN-PT Transparent Ceramics with Ultra-High Electro-Optic Effect and Its Application in Optical Devices

Transparent electro-optic (EO) ceramics of La-doped 0.75Pb(Mg1/3Nb2/3)O-3-0.25PbTiO(3) (0.75PMN-0.25PT) were prepared successfully. High transparency of 69% in the near-infrared (IR) wavelength (1550 nm) was achieved at 2 mol% La doping, meanwhile it shows an extremely high quadratic EO coefficient of 45.4x10(-16) m(2)center dot V-2, which is indispensable for applications in EO devices. The distribution of a polar nanodomain structure of the samples experiences disorder-order-disorder evolution in a La doping range. It is found that a parallelly-stacked polar nanodomain structure with an easier and faster polarization switching in the 2 mol% La-doped sample suggests that an ordering distribution of polar nanoregions would be critical to inducing large EO effect, transparency, and piezoelectric response. A triple-cavity tunable optical filter (TOF) with a single transmission peak and a tuning voltage below 30 V in a tuning range of 190-197 THz was designed based on our ceramics. The work is believed to bridge the relationship among doping-engineering, EO properties, and polarization behavior, which would guide the further optimization of transparent EO ceramics.