Zhang JianWei, Du XaioPing, Zhao JiGuang, Wang XuPing, Liu Bing, Song YiShuo, Liu ZhengJun, Chen Hang
Opt Lett. 2022 Jul 15;47(14):3467-3470. doi: 10.1364/OL.460885.
Recent experiments have revealed that the order of the electro-optic (EO) effect depends on the frequency of electric field in paraelectric nanodisordered KTaNbxO (KTN) crystal. Through the dielectric frequency spectrum under the bias electric field, enormous linear and quadratic EO effects were discovered at the resonance frequencies, which changed the perception that only the quadratic EO effect exists. Applying just a small AC electric field of 6 V/mm, the effective linear EO coefficient reached 478 pm/V at 609 kHz, and the effective quadratic EO coefficient reached 4.39*10mVat 302 kHz. The reason why an extremely low electric field results in an enormous EO coefficient is attributed to the resonance between the polar nanoregions (PNRs) and the electric field, induced by the field-driven reorientation of free dipoles on the boundary of the PNRs. In addition, the order of EO effect depending on the frequency of electric field was attributed to the motion modes of the PNR. This finding improves the understanding of how the EO effect is caused by field-driven PNR dynamics, but also provides a basis for the development of EO devices.
最近的实验表明，在顺电体纳米无序KTaNbxO（KTN）晶体中，电光（EO）效应的阶数取决于电场频率。通过在偏置电场下的介电频谱，在共振频率处发现了巨大的线性和二次电光效应，这改变了人们认为仅存在二次电光效应的观念。仅施加6 V/mm的小交流电场，在609 kHz时有效线性电光系数达到478 pm/V，在302 kHz时有效二次电光系数达到4.39×10 mV。极低电场导致巨大电光系数的原因归因于极性纳米区域（PNR）与电场之间的共振，这是由PNR边界上自由偶极子的场驱动重新取向引起的。此外，电光效应的阶数取决于电场频率归因于PNR的运动模式。这一发现不仅增进了对场驱动PNR动力学如何引起电光效应的理解，也为电光器件的发展提供了基础。
