Effect In LiNbO3 Research Articles

Optimization of transverse electro-optic effect in LiNbO3 and LiTaO3 crystals

Optimization of transverse electro-optic effect in LiNbO3 and LiTaO3 crystals

Effect of LiNbO3 on the electrocaloric performance of 0.94BNT-0.06BT ceramic materials

Considering that the electric refrigeration temperature range of 0.94BNT-0.06BT ceramic materials is 100 ∼ 140 °C, the electric refrigeration performance of the 0.94BNT-0.06BT ceramic material system was modified by LiNbO3 doping to reduce the cooling temperature. As a result, the refrigeration temperature range of the 0.94BNT-0.06BT ceramic material system was lowered to 25 ∼ 80 °C, achieving its cooling effect near room temperature, and in this temperature range, the adiabatic temperature changes ΔT > 0.6K.

Bulk piezo-photovoltaic effect in LiNbO3

The deformations arising in iron-doped lithium niobate crystals (LiNbO3:Fe) under laser illumination were registered by changes in the parameters of X-ray diffraction rocking curves. The piezoelectric deformation as a result of the bulk photovoltaic effect was separated from heating according to the different kinetics of these processes using a set of time-resolved X-ray diffraction techniques. The dependence of the peak shift on the diffraction order confirmed the manifestation of the bulk piezo-photovoltaic effect. Additionally, the measurements of an external electric field influence on the diffraction peaks parameters were carried out as well as the measurements of the electrophysical and bulk photovoltaic characteristics of the crystal.

Tunable Ultraviolet Photorefractive Effect in LiNbO3/TiO2‐X (X = Pd or N): Theoretically Prediction and Experimental Validation

In this study, the introduction of unoccupied or partially occupied surface states energy levels into TiO2 upon Pd or N modification, respectively are theoretically predicted, suggesting a tunable carriers behavior in LiNbO3/TiO2‐X (X = Pd or N) composites. Inspired by the theoretical simulation, a new low‐cost method of compositing LiNbO3 with TiO2‐X (X = Pd or N) to mediate the ultraviolet photorefraction of LiNbO3 is proposed. The experimental results indicate that LiNbO3/TiO2 and LiNbO3/TiO2‐Pd show enhanced photorefraction due to reduced recombination of photoinduced carriers or increased free holes in LiNbO3. While LiNbO3/TiO2‐N exhibits photorefraction resistance since the photoinduced holes in LiNbO3 would get trapped by NOX species at the interface. This study will not only provide a simple way to fabricate tailored photorefractive material, but also offer new insights into the mechanism of photorefraction and photorefractive material design method.

Ptychographic analysis of the photorefractive effect in LiNbO3:Fe.

We present light induced refractive index changes in iron doped lithium niobate detected with a novel microscopy technique called ptychography. This method determines the change of the refractive index together with the intensity distribution of the writing beam from a single scan with a reconstructed spatial resolution of 3 μm and a sensitivity of the refractive index change of 10-5. We show that the light induced refractive index change is strongly connected to the intensity shape of the writing beam and that it shows the expected nonlocal behaviour. Applying the novel method to the investigation of the photorefractive effect offers an excellent opportunity to study this nonlocal response to the spatial distribution of the writing beam.

Dual LiNbO3 Crystal-Based Batteryless and Contactless Optical Transient Overvoltage Sensor for Overhead Transmission Line and Substation Applications

Advanced high-voltage and overvoltage measurement techniques are required for smart grid construction. The existing overvoltage measurement methods that are currently used for power system measurements are mostly based on the use of electromagnetic voltage transformers and capacitive voltage transformers, which have contradiction in measuring accuracy, measuring distance, antijamming, and system compatibility. A batteryless sensor for contactless measurement of the overvoltage on overhead transmission lines based on a combination of the electrooptic effect in LiNbO3 with stray capacitance in the air is designed in this work. On the basis of this design, a dual-crystal structure-based electrooptic conversion unit is presented that eliminates the natural birefringence and improves the operating stability of the sensor. Testing platforms were set up to measure the characteristics of the sensor in thermal stability. In combination with a data acquisition device, the newly designed sensor was applied to online monitoring of the overvoltage in the ac bus and the overhead transmission lines of a 500-kV transformer station and a ±500-kV convertor station in the China Southern Power Grid.

Design and simulation of pressuresensor and accelerometer based on integrated optical circuits using photoelastic effect of LiNbO3

Abstract In this paper a novel optical pressure and acceleration sensor based on micro electro mechanical systems (MEOMS) has been designed. For this purpose an integrated MachZander interferometer has been used in LiNbO3 diaphragm. In this sensor, the strain caused by applied pressure or acceleration leads to a change in refractive index of the wave guide in the diaphragm due to the photoelastic effect. The refractive index change leads to a phase change in the light wave that propagates in the waveguide. This phase change is converted to intensity change using the MachZander interferometer. The software ANSYS 14.5 was used for calculation of the strain in the diaphragm .The pressure and acceleration sensitivity of the designed sensor have been obtained 2.33×10-4 (rad /Pa) and 2.16×10-5 (rad.s2/m), respectively.

Electric field tuning characteristic of multiple optical parametric oscillator based on MgO:QPLN

The quasi-phase matching optical parametric oscillator tuning methods, i.e. grating period tuning, temperature tuning, pumping wavelength tuning, and angle tuning are more simple and convenient than the traditional mechanical tuning which requires inserting the frequency selective element into the cavity. However, itneed to be improved for wavelength tuning in quick response and high-accuracy control. In this paper, the tunability of multiple optical parametric oscillator (MOPO) based on MgO:QPLN has been studied under an applied electric field. Based on the linear electro-optic effect of LiNbO3, we theoretically analyze the feasibility of achieving parametric light wavelengths tuning by applying electric field of particular direction on the z-direction of LiNbO3. We study the relationships between the ability of electric field tuning and the polarization structure parameters, and analyze the feasibility of MgO:QPLN with high positive and negative superlattice domain ratio for electric field tuning. The relationship of output wavelength and loading voltage is achieved by simulation. Simulation results show that the tuning rates of 1.57 μm signal light and 3.84 μm idler light are about 0.27 and 0.93 nm/kV, respectively. By reasonably controlling the temperature of MgO:QPLN crystal, tuning sections of the parametric light electric field could be linked orderly, and the output wavelength of parametric lights could be turned continuously in a wide range, which greatly expands the spectral bandwidth of the electric field tuning. In the experiment, a high-repetition-rate acousto-optic Q-switched Nd:YVO4 laser at 1064 nm is applied as the pumping source. The laser works at 200 kHz with a pulse width of 9.756 ns and its maximumouput power is 22.8 W on average. When the temperature of MgO:QPLN is stable at 20℃, the average output power of 1.57 μm signal light and 3.84 μm idler light are 1.7 and 0.72 W, respectively, and the corresponding pulse width of the two parametric lights is 9.132 and 8.463 ns. By loading proper electric field on MgO:QPLN (on-load voltage：-3000 V-+3000 V), we achieve the electric tuning of the parametric light at 3.84 μm range, and the bandwidth of spectral tuning is about 6 nm with the tuning rate approaching 1 nm/kV. Combining the temperature tuning with the electric field tuning, we further achieved high-precision continuous tuning of the parametric light in a wide spectrum range. All the final experimental results agree basically with the theoretical analysis one. In addition, results show that the electric field tuning performs better than the temperature tuning in accuracy control and quick response. For MgO:QPLN-MOPO, its irregular domain configuration could work adequately by introducing the electric tuning.

Phase transitions, relaxor behavior, and large strain response in LiNbO3-modified Bi0.5(Na0.80K0.20)0.5TiO3 lead-free piezoceramics

The effect of LiNbO3 (LN) addition on the ferroelectric behavior and piezoelectric properties of Bi0.5(Na0.80K0.20)0.5TiO3 (BNKT20) lead-free piezoceramics were systematically investigated. Results showed that the LN substitution into BNKT20 induced a transition from coexistence of ferroelectric tetragonal and rhombohedral phases to relaxor pseudocubic phases, which is accompanied by the significant disruption of ferroelectric order and with the shift of the ferroelectric-relaxor transition temperature TF-R down to room temperature. Accordingly, a large accompanying normalized strain of ∼0.38% (corresponding to a large signal d33* of ∼475 pm/V) were obtained in BNKT20 with 2.5 mol. %LN addition near the phase boundary. Temperature-dependent measurements of both polarization and strain from room temperature to 120 °C suggested that the origin of the large strain is due to a reversible field-induced ergodic relaxor-to-ferroelectric phase transformation. Moreover, an attractive property for application as high-temperature dielectrics was obtained in this system modified with 8 mol. %LN with a high permittivity of 1760 ± 15% from room temperature up to 500 °C, spanning a range of about 450 °C.

Role of particle anisotropy and deposition method on the patterning of nano-objects by the photovoltaic effect in LiNbO3

Novel experiments and data analysis on the emergent use of evanescent photovoltaic fields generated by visible illumination of Fe:LiNbO3 for trapping, patterning and massif manipulation of micro-and nano-objects are reported. The data include experiments on a variety of particles (dielectric and conductive) and illumination geometries. The data reveal the key role of several physical parameters such as the modulation m of the exciting light pattern, particle anisotropy and deposition method. The observed dependences are satisfactorily described within a theoretical framework describing the dielectrophoretic forces acting on the substrate surface.

Effects of LiNbO 3 substitution on lead-free (K 0.5Na 0.5)NbO 3 ceramics: Enhanced ferroelectric and electrical properties

To know the effect of LiNbO 3 substitution, lead-free (1 − x)(K 0.5Na 0.5)NbO 3- xLiNbO 3 (KNN:LN) ceramics were prepared by the solid-state reaction method. The crystallized phase and grain morphology of the KNN:LN ceramics were confirmed by X-ray diffraction and SEM studies, respectively. The dielectric and electrical properties were investigated as a function of the frequency and the temperature. The small LiNbO 3 substitution decreased dc electrical conductivity and exhibit well-saturated ferroelectric P-E hysteresis loops. The effects of LiNbO 3 substitution on crystallized phase, grain morphology, ferroelectric and electrical properties are discussed.

Linear and nonlinear discrete light propagation in weakly modulated large-area two-dimensional photonic lattice slab in LiNbO_3:Fe crystal

A weakly modulated large-area two-dimensional square photonic lattice slab was fabricated through optical induction technique in a photorefractive photovoltaic LiNbO(3):Fe crystal. Bragg-matched diffraction technique was used to characterize the square photonic lattice slab. Interestingly, linear discrete diffraction typical for waveguide arrays was observed in such a square photonic lattice slab, indicating that the lattice slab can be viewed effectively as a one-dimensional waveguide array. Furthermore, discrete soliton was demonstrated in the photonic lattice slab due to a saturable self-defocusing nonlinearity arising from the bulk photorefractive photovoltaic effect of LiNbO(3):Fe.

Photoelectric effects of ultraviolet fast response and high sensitivity in LiNbO3 single crystal

The photoelectric effects in LiNbO3 (LNO) single crystal have been systematically studied with the two kinds of LNO wafers of tilt of 10° and untilted at the ambient temperature. The ultrafast response photoelectric effect of 120 ps rise time was observed in 10° tilted LNO single crystal with a 266 nm laser pulse of 25 ps duration. The photocurrent responsivity of untilted LNO with an interdigitated electrode of 10 μm finger width and 10 μm interspacing is 17.1 mA/W under the irradiation of 300 nm wavelength UV light at 10 V bias. The noise current under sunlight is only 73 pA at 10 V bias. The experimental results suggest that the LNO single crystal is one of the promising materials for photodetectors working in UV region.

Phase transitional behavior and piezoelectric properties of BiYbO 3–Pb(Ti 0.5Zr 0.5)O 3–LiNbO 3 ceramics

Perovskite (1 − x)(0.06BiYbO 3–0.94Pb(Ti 0.5Zr 0.5)O 3)– xLiNbO 3 (BYPTZ-LN) ceramics were synthesized by the conventional ceramic processing. The effect of LiNbO 3 on the microstructure and piezoelectric properties was investigated. The perovskite phase and the Yb 2Ti 2O 7 pyrochlore phase are coexisting in the BYPTZ-LN ceramics sintered at 1140 °C. The material with perovskite structure is tetragonal at x ≤ 0.04 and becomes single rhombohedral at x ≥ 0.08. A morphotropic phase boundary between rhombohedral and tetragonal phases is found in the composition range 0.04 ≤ x ≤ 0.08. Analogous to Pb(Zr,Ti)O 3, the piezoelectric and electromechanical properties are enhanced for compositions near the morphotropic phase boundary. Piezoelectric constant d 33 values reach 290–360 pC/N. Electromechanical coefficients k p reach 0.38–0.55. The maximum values of d 33, k p and P r are obstained as x = 0.08, accompanying with the minimum values of Q m and E c. The Curie temperature T c and the maximum value of dielectric constant decrease with increasing LiNbO 3 content. BYPTZ-LN ceramics with the high d 33 value and the high thermal-depoling temperatures of >320 °C are obtained.

UV-photorefractive effect in LiNbO 3:Ce:Mn single crystal

In this paper, the ultraviolet (UV) photorefraction effect of lithium niobate doubly doped with Ce and Mn has been investigated. It is found the diffraction efficiency shows oscillating behavior under UV-light-recording. A model based on electrons and holes as the dominant carriers is proposed to study the oscillatory behavior of the diffraction efficiency. On the basis of the material equations and the coupled-wave equations, we found that the oscillatory behavior is due to the oscillation of the relative spatial phase shift Φ. And the electron–hole competition may cause the oscillation of the relative spatial phase shift. This oscillation behavior is different from that caused by very high-strength space electric field. UV recording can suppress the beam-fanning perfectly, and the most important is the high sensitivity.

Two-center holographic recording in highly doped LiNbO3 crystals

In this paper, we report the observation of electron tunneling during two-center recording in LiNbO3:Fe:Mn doped with high Fe concentration. Unlike tunneling in the singly doped lithium niobate that erases the hologram, the effect in two-center recording can improve the diffraction efficiency of the hologram after the recording while it is kept in the dark. A detailed study of this effect in LiNbO3:Fe:Mn is presented both theoretically and experimentally. We show that the hologram strength may increase or decrease due to tunneling, depending on the experimental condition of recording.

Three-dimensional write–read–erase memory bits by femtosecond laser pulses in photorefractive LiNbO3 crystals

We report on a three-dimensional single-shot optical recording by 150fs pulses at 800nm wavelength in Fe-doped and stoichiometric undoped LiNbO3. The highest refractive index modulation of ∼10−3 per single pulse has been achieved at close to the dielectric breakdown irradiance of ∼TW/cm2, and was found to be independent of polarization of the writing beam. The quasi-permanent and rewritable bits have been demonstrated in Fe-doped LiNbO3. Recording in undoped stoichiometric LiNbO3 was of transient nature with full optical contrast recovery on a 0.1–1s scale. The observed refractive index modulation is explainable by the photovoltaic effect in LiNbO3.

Comparative Study of Composition Dependences of Photorefractive and Related Effects in LiNbO3 and LiTaO3 Crystals

The results of a comparative study of composition dependences of the light-induced refractive index change, photorefractive sensitivity, polaron luminescence, and intrinsic optical absorption in nominally pure LiNbO 3 and LiTaO 3 crystals are reported. Our investigation demonstrates that the particular light-induced defects traced by the photoluminescence are secondary photorefractive centers itself. The experimental results obtained are well described by light-induced dissociation of bipolarons into small polarons that are unstable at room temperature.

Investigation of the Piezoelectric Effect in LiNbO3 and LiTaO3 Crystals by X-Ray Diffraction

The behavior of LiNbO3 and LiTaO3 crystals with domain structures in an external electric field was studied using high-resolution X-ray diffractometry and topography. Domain structures in Z-cut LiTaO3 and Y-cut LiNbO3 crystals have been formed by the aftergrowth thermoelectricall treatment technique were investigated. Strong elastic distortions near different domain boundaries in the Y-cut LiNbO3 crystal were detected. The possibility of using X-ray diffraction to measure piezoelectric charge constants tensor components is demonstrated.

Photochromic effect in LiNbO_3: Fe :Co

In this paper, Co(2)O(3) was codoped in LiNbO(3): Fe crystals. It was found that Co codoping can give rise to the strong photochromic effect in LiNbO(3): Fe. Based on the UV-VIS-NIR absorption spectra, photorefractive sensitivities, and EPR results for both virgin and sensitized states of the crystal, the photochromic mechanism in this material was suggested as follows. During sensitization, electrons transfer from O(2-) to Fe(3+) directly while holes are thermally excited from O- into the valence band and then partly trapped by Co(2+), which leads to the darkening of the crystal. In bleaching process, the electrons are excited from Fe(2+) to the conduction band by green light and recombine with the holes on the Co(2+) level. Sensitizing/bleaching experiments were also carried out in LiNbO(3): Fe: Co crystals. Fast sensitization found for this material is beneficial to two-color recording.