Observation of an intrinsic nonlinearity in the electro-optic response of freezing relaxors ferroelectrics

Abstract

We demonstrate an electro-optic response that is linear in the\ud amplitude but independent of the sign of the applied electric field. The\ud symmetry-preserving linear electro-optic effect emerges at low applied\ud electric fields in freezing nanodisordered KNTN above the dielectric peak\ud temperature, deep into the nominal paraelectric phase. Strong temperature\ud dependence allows us to attribute the phenomenon to an anomalously\ud reduced thermal agitation in the reorientational response of the underlying\ud polar-nanoregions

Macroscopic response and directional disorder dynamics in chemically substituted ferroelectrics

“…In fact, it is well known that in a perovskite structure the ion disposition in the ABO 3 lattice may be distorted, causing local inherent or internal dipolar disorder [19,20]. When a substitutional disorder is simultaneously present, below the so-called Burns temperature T B , its combination with this internal disorder can give rise to lattice distortions, strains, and local electric fields [21], which then lead to PNRs [3,5,[22][23][24]. Moreover, the growth process along a specific direction (say c) is known to strongly influence the defects and the distributions of strains and charges even though the crystal is never poled [25,26].…”

Dynamic response of polar nanoregions under an electric field in a paraelectric KTa0.61Nb0.39O3 single crystal near the para-ferroelectric phase boundary

“…Recently, KTa 1− x Nb x O 3 (KTN)-based single crystals have attracted much scientific attention owing to their excellent quadratic electro-optic (QEO) and electrostrictive effects123456789. Abundant devices such as electro-optic (EO) switches, deflectors and modulators based on KTN crystals have been designed and fabricated46789.…”

“…Besides, the Li: KTN crystal has been used to develop scale-free optics, which could lead to a completely new paradigm for ultraresolved imaging and microscopy1213. The origin of the giant QEO effect and novel scale-free optics in paraelectric KTN have been attributed to the presence of polar nanoregions (PNRs) near the para-ferroelectric phase boundary1231213. Unfortunately, the mechanism with which PNRs contribute to these phenomena is still unclear.…”

“…Unfortunately, the mechanism with which PNRs contribute to these phenomena is still unclear. Present research on the QEO effect in KTN mainly investigates DC or low-frequency (<500 Hz) electric fields1234, whereas research on the QEO effect under higher-frequency electric fields should be performed to promote the implementation of KTN in broadband optical communications. Furthermore, the investigation of the QEO effect under wide-frequency-range electric fields could facilitate the interpretation of the dynamic response of PNRs, which is also associated with other related interesting phenomena, like scale-free optics.…”

Continuous Solitons in a Lattice Nonlinearity

“…The Curie point at the temperature T C ¼ 294 K is measured and characterized through low-frequency dielectric spectroscopy that also signals the absence of large deviations from the mean-field behavior, typical of other near-transition disordered ferroelectric samples [16,17]. The sample is grown so as to manifest a sinusoidal variation in the low-frequency dielectric constant [18][19][20].…”