Elasto‐optic materials have extensive applications, particularly in sensors, filters, and acousto‐optic modulators in optical–mechanical‐coupled devices. Ferroelectric phenomenological theoretical analyses have shown that materials with large ferroelastic responses also have high elasto‐optic effects, and morphotropic phase‐boundary (MPB) ferroelectrics have substantial ferroelastic coupling; thus, a large elasto‐optic effect can be obtained. In this study, guided by phenomenological theories, lanthanum‐modified lead zirconate–lead titanate (PLZT) transparent ceramics close to MPB are successfully prepared using the hot‐pressing method. The elasto‐optic properties of the PLZT transparent ceramics are investigated using the half‐wave stress and the Sénarmont compensator methods. The results indicate that the PLZT ceramics have high transmittance (higher than 70% in near‐infrared) and a large elasto‐optic effect with a stress‐optic coefficient of 10.41 × 10−12 m2 N−1 (approximately three times that of SiO2). Based on these properties, intensity‐ and interference‐type optical‐stress sensors are designed and realized; better anti‐interference ability can be achieved using the interference‐type sensor. These results indicate that PLZT transparent ceramics are promising candidates for optical–mechanical‐coupled device applications. This study also substantiates that transparent ceramics are novel elasto‐optic materials, which uncover new avenues for the development of elasto‐optic materials with excellent properties.

Elasto‐Optic Effect of Lanthanum‐Modified Lead Zirconate–Lead Titanate Transparent Ceramics: Application in Optical‐Stress Sensors

Strong mid-infrared pulses are used to directly control the dynamics of the crystal lattice. In this paper, we studied the effects of Sb3+, Nb3+ and V3+ atom doping on the ferroelectric dynamics of cubic KTaO3 induced by mid-infrared light through the nonlinear coupling of phonon modes. We found that Nb3+ and V3+ doping cause the coupling constant l between the highest (Qhx) and lowest frequency phonon mode (Qlz) to be negative, which results in a softening of the Qlz mode when the Qhx mode is externally pumped; Sb3+ doping will increase the damping effect and inhibit the occurrence of KTaO3 light-induced ferroelectricity; and it is proved that the two different configurations of doped KTaO3 compounds can suppress or enhance the photo-induced ferroelectricity of KTaO3. KTaO3-defect-1 doped with V3+ can cause the light-induced ferroelectricity of KTaO3, but KTaO3-defect-2 doped with V3+ inhibited it. In short, our research results strongly support the idea of using atomic doping to control the photo-induced ferroelectricity of KTaO3, which provides an effective strategy for using the light-induced ferroelectricity in all-optical devices.

Regulation of Nb3+, Sb3+ and V3+ doping on the photo-induced ferroelectricity of KTaO3

In recent years, many novel optical phenomena have been discovered based on perovskite materials, but the practical applications are limited because of the difficulties of device fabrication. Here, we propose a method to directly induce localized lattice modification inside the potassium tantalate niobate crystal by using the femtosecond laser. This selective modification at the processed regions and the surrounding areas is characterized by two-dimensional Raman spectrum mapping. The spectrum variations corresponding to specific lattice vibration modes demonstrate the lattice structure deformation. In this way, the lattice expansion at the femtosecond laser irradiated regions and the lattice compression at the surrounding areas are revealed. Furthermore, surface morphology measurement confirms this lattice expansion and suggests the extension of lattice structure along the space diagonal direction. Moreover, the existence of an amorphization core is revealed. These modifications on the sample lattice can induce localized changes in physicochemical properties; therefore, this method can realize the fabrication of both linear diffraction and nonlinear frequency conversion devices by utilizing the novel optical responses of perovskite materials.

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Femtosecond Laser Induced Lattice Deformation in KTN Crystal

Cu-Doping-Modified Order State, Ferroelectric Property, Multiscale Inhomogeneities, and Local Structure in the Relaxor KTa1–xNbxO3 Crystal

This letter reports the two-wave mixing experimental results of tetragonal Fe-doped KTa1-xNbxO3. A 7.3 cm-1 gain coefficient and 42% diffraction efficiency have been obtained. For the first time internally self-pumped phase conjugation is being observed in this crystal. At room temperature, the conjugate reflectivity measured is 21%.

Photorefractive properties and self-pumped phase conjugation of tetragonal fe-doped kta1-xnbxo3 crystal

Growth and characterization of large size lead-free ferroelectric K(Ta,Nb)O3 single crystal

https://iopscience.iop.org/article/10.1149/2162-8777/abddd5/pdf

First-Principles Calculation of Defect Properties on Copper Doped KTaO3 Crystal

An electro-optic modulation system was adopted for measuring the quadratic electro-optic coefficient of KTN crystal. Theoretical analysis and experimental results verified the feasibility of this method. The quadratic electro-optic coefficient of a KTN crystal chip, which has a Curie temperature of 0 °C, was measured using this system in the temperature range of 2 °C to 18 °C (Tc = 0 °C). The influences of temperature, AC voltage and frequency on the quadratic electro-optic coefficient were discussed. It was found that the relaxation effect of PNRs (polar nano-regions) played an important role in the determination of the quadratic electro-optic coefficient of KTN crystal.

Lie-Kun Yang

Papers

Growth and characterization of large size lead-free ferroelectric K(Ta,Nb)O3 single crystal

First-Principles Calculation of Defect Properties on Copper Doped KTaO3 Crystal

Measurement of the Quadratic Electro-Optic Coefficient of KTN Crystal with an Electro-Optic Modulation System in the Presence of Polar Nano-Regions