LAUSR

Abstract Potassium tantalate niobate, KTa1-xNbxO3 (KTN), exhibits a giant electro-optic effect with unique features. However, its relatively-low optical transmittance limits its practical applications in functional devices. Here, we report the observation of high optical transparency induced by either alternating current (AC) or direct current (DC) electric fields. The AC field induces a rapid phase transition to the paraelectric phase in KTN which has much high optical transmittance compared to its initial ferroelectric phase. On the other hand, the DC electric field causes effective alignment of all dipolar clusters to form a uniform monodomain ferroelectric state, enabling high optical transparency without any optical scattering. More importantly, the high optical transparency in this monodomain ferroelectric phase can be preserved extremely well in a certain period even after turning off the applied DC voltage. We further study the effect of KTN bandgap on the optical transmittance with and without the electric fields. It is interesting that the bandgap energy with the AC electric field is less than that with the DC electric field. Our results are important for better understanding the phase-transition mechanism under electric fields. Also, high optical transparency is much desired for device applications with improved performances.