Lithium Tantalite Research Articles

Ultra‐Low‐Power Tunable Topological Photonic Filter on Hybrid Integrated Lithium Tantalite and Silicon Platform

AbstractIntegrated tunable optical filters are essential components in photonic signal processors, telecom systems, sensors, and quantum optical devices. Two of the most important features of a tunable filter are its dimensions and power consumption. Herein, the design and experimental validation of an on‐chip optical filter composed of a 1D topological photonic crystal cavity based on a hybrid integrated lithium tantalite‐silicon platform is presented. The strong optical confinement of the boundary state allows the fabrication of a tunable filter with an ultra‐compact size of 1.14 × 75 µm2 is demonstrated. Moreover, lithium tantalite has excellent electro‐optic properties and enables ultra‐low‐power wavelength tuning of the topological boundary state. The measured power consumption and tuning efficiency of the device are 0.0218 nW pm−1 and 6.64 pm V−1, respectively. The anisotropy of thin‐film lithium tantalite is verified by evaluating its tuning efficiency at different optical angles. The device can compensate for thermally induced refractive index changes ≈20 °C, exhibiting operational robustness. High‐speed transmission experiments confirm the stability of the developed tunable filter. This optical filter implements a topological structure with a compact size and can potentially be applied in on‐chip quantum optics, nonlinear optics, and optical sensing.

Kinetic Modeling and Material Removal Mechanism Analysis of Fixed-Abrasive Polishing for Lithium Tantalite Wafer

As a typical multi-functional soft-brittle material, lithium tantalate (LT) exhibits excellent electro-optical and ferroelectric properties and now has been widely applied in many fields, such as electro-optical modulators, pyroelectric detectors, and surface acoustic wave substrates. Traditional free-abrasive polishing processing of lithium tantalite crystals is generally fraught with poor efficiency for its lower fracture toughness. This study proposed a method of polishing lithium tantalite wafer by means of fixed-abrasive plates. A cutting force model and the relative cutting speed model of the machining mechanism of fixed-abrasive plates were first established, and then the main influencing factors of cutting force and relative cutting speed were analyzed on the basis of the theoretical model. It was found that cutting force is influenced by eccentricity and load, while relative cutting speed is influenced by eccentricity and the fixed-abrasive plates’ rotation speed. Finally, single-factor tests were conducted on these influencing factors, and the comparative analysis between the experimental results and those in the theoretical model shows that they are highly correlated to each other. After 30 min of polishing under the optimized parameters w = 60 rpm, e = 90 mmand applied with variable load, the surface roughness S a of the workpiece can be reduced to 1.234 nm, and the MRR reaches 14.821 μm/h.

Hybrid lithium tantalite-silicon integrated photonics platform for electro-optic modulation.

Integrated electro-optic modulators are key components in photonic integrated circuits. Silicon photonic technology is considered to be promising for large-scale and low-cost integration. However, silicon does not exhibit any Pockels effect, and the electro-optic modulator based on free-carrier dispersion suffers from challenges such as high-power consumption, limited bandwidth, and large optical propagation loss. Here, a new, to the best of our knowledge, hybrid lithium tantalite-silicon platform is proposed for electro-optic modulators based on the Pockels effect. Benefiting from the strong Pockels coefficients of a thin-film lithium tantalite, a hybrid microring-based modulator is demonstrated. The quality factor and the extinction ratio of the hybrid microring are 1.7 × 104 and 10 dB, respectively. The linear bidirectional wavelength tuning efficiency is measured as 12.8 pm/V. The measured 3-dB bandwidth is > 20 GHz. High-quality eye diagrams of 20 Gbps non-return-to-zero signal and 20 Gbps four-level pulse amplitude modulation signals are generated experimentally. The proposed platform extends the toolbox of silicon photonics technology, which paves the way for high-speed modulators and phase shifters in optical communication and optical phased array.

An Analysis of Edge Chipping in LiTaO3 Wafer Grinding Using a Scratch Test and FEA Simulation

Lithium tantalite (LiTaO3) is a representative multifunctional single-crystal material with electro-optical, acoustic, piezoelectric, pyroelectric, and nonlinear optical properties used as a substrate for surface acoustic wave (SAW) devices. To enhance SAW device performance, thinner LiTaO3 substrates with improved surface roughness are desired. Chemical mechanical polishing (CMP) is employed to achieve the desired surface roughness after grinding. However, the thinning process increases the risk of substrate fracture, especially at the edges, resulting in edge chipping. Edge chipping can lead to complete substrate failure during SAW device fabrication, requiring an effective wafer geometry to prevent it. The study utilizes scratch tests and finite element analysis (FEA) to identify the optimal edge shape (C-cut, trimmed, and thinned) for preventing edge chipping on LiTaO3 wafers. The C-cut edge refers to the rounding of the wafer’s edge, while the trimmed edge refers to the machining of the wafer’s edge to be perpendicular to the wafer surface. As a result of the scratch tests, we observed edge-chipping lengths of 115 and 227 μm on the C-cut and trimmed edges, respectively, while the thinned edge (half C-cut) resulted in complete wafer fracture. In the finite element analysis (FEA), edge-chipping lengths of 80, 120, and 150 μm were obtained on the C-cut, trimmed, and thinned edges (half C-cut), respectively. In conclusion, it has been confirmed that the C-cut, trimmed, and thinned edge shapes are effective in preventing edge chipping. However, considering that the C-cut edge shape becomes thinner through grinding, using the trimmed edge shape appears to be the most effective.

Improvement of Overlap for 2x2 MZI Electro-Optic Switch Based on Lithium Tantalite (LiTaO3)

This research introduces a method of an electro-optic effect and electro-refractive effect that considers very imperative for high-speed optical communication systems. In this research, it presents way by a reduction the gap between the electrodes d, and this technique achieves to solve the problem of overlap for Mach-Zehnder interferometer MZI electro-optical switch base on lithium tantalite LiTaO3, also this technique suggests a model for analysis the effect parameters on the electro-optic overlap of the electro-optic switch as the ordinary positive changing of refractive index and a length of arm switch. This study achieves a better overlap by large positive changing refractive index with a suitable small length of arm about 8µm and low driving power at least 4V/µm. Also, for lithium tantalite LiTaO3, this research achieves a better performance for system using the near infrared wavelength.

Distributed Nonlinear Model and Fast Analysis for In-Band IMD3 Prediction of Surface Acoustic Wave Resonators.

The motivation of this work is to analyze the in-band intermodulation distortion (IMD) occurring in surface acoustic wave (SAW) devices, using a recently developed fast method based on the input-output equivalent sources (IOES). The method calculates the equivalent current sources of a given harmonic (H) or IMD, which when applied at the boundaries of any uniform nonlinear region produce the same nonlinearities as the full distributed circuit. The accuracy of the method is validated with a very simplified SAW resonator with ten digits, which is modeled by a discretized Mason-based circuit. The IOES method provides equal results to the ones obtained through harmonic balance (HB) simulations, performed by means of commercial software, being the first 1000 times faster. Once the accuracy of the method is guaranteed, it is used to analyze the measured in-band IMD3 of several lithium tantalite 42° cut leaky SAW (LSAW) resonators with different pitches and duty factors at the B66 long term evolution (LTE) frequency band. Those resonators are comprised of 100 and 20 electrode pairs for the active region and each of the reflectors, respectively, which implies the analysis of a very large distributed nonlinear problem with thousands of nonlinear local sources. The IOES method takes 35.4 s in simulating 51 frequency points, whereas this simulation is not possible using a commercial HB simulator on a general-purpose computer.

Efficient second harmonic generation of a Yb fiber-based amplified stimulated emission source

Efficient second harmonic generation (SHG) of ytterbium (Yb)-doped fiber-based amplified spontaneous emission (ASE) light with temporally low coherence is reported. A Yb-fiber ASE light with a tunable bandwidth was amplified in two power amplifier stages and was frequency-converted by a periodically-poled lithium tantalite waveguide. The second harmonic conversion efficiency of the ASE light achieved in the experiment was inversely proportional to the bandwidth, which was in very good agreement with theoretically calculated value using the self-convolution relationship of the power spectral density for nonlinear frequency conversion of low coherent light. The prospects for further improvement in nonlinear frequency conversion of the fiber ASE source will be discussed.

Structural and photoelectric properties the thin film ZnO on LiTaO-=SUB=-3-=/SUB=- substrate

The results of the study of the structural and photoelectric properties of the ZnO-LiTaO3 thin-film structure are presented. The results X-ray structural analysis and results atomic-force microscopy of the surface zinc oxide thin films synthesized on a single-crystal lithium tantalite substrate and on a KU-1 quartz substrate are presented. The spectral dependence of photoconductivity in the thin film structure of ZnO-LiTaO3 and the structure of ZnO-quartz in the ultraviolet and visible spectral ranges are presented. Keywords: zinc oxide, laser ablation, ferroelectric materials, X-ray structural analysis, atomic-force microscopy surface, photoconductivity, method Tikhonov-Lavrentiev regularization.

The Effect of Cerium Doping on LiTaO3 Thin Film on Band Gap Energy

Lithium tantalite LiTaO3 was grown on a Si Type-P (100) substrate by chemical solution deposition and spin coating methods at a speed of 3000 rpm for 30 seconds with an annealing temperature of 800 ° C, 900 ° C. This study aims to determine the effect of temperature variations on the band gap energy. The results show that the energy band gap value of the thin film has a significant impact on the interpretation of annealing temperature. It can be seen that a high energy band gap peak occurs at an annealing temperature of 900 ° C and a time of 15 hours of the energy band gap of 1,49 eV. This shows the effect of temperature variations on the energy band gap to move from the valence band to the conduction band, which will produce current.

Crystallographic orientation effect on the polishing behavior of LiTaO3 single crystal and its correlation with strain rate sensitivity

Lithium tantalite (LiTaO3 or LT) single crystal has been extensively applied in the fields of electro-optical and piezoelectric devices. As a typical anisotropic material, the crystallographic orientation effect on its machining responses, i.e., surface roughness and material removal rate (MRR), is not yet well understood. In the present work, we investigated the polishing responses of the three typical crystallographic orientations for LT single crystal under a series of rotation speeds. The results showed that both the rotation speed and crystalline orientation had little effect on the quality of polished surface. While for the MRR, it was almost linearly increased with increasing rotation speed for all of the three planes, among which the enhancements of MRR on Y-42° and Y-36° planes were more pronounced than that on X-112° plane. The scratch features and friction coefficients were investigated using a nanoindentation system under various velocities. The nano-hardness values were obtained under various strain rates and, hence, the strain rate sensitivities (SRS) were determined as 0.0172, 0.0455, and 0.043 for X-112°, Y-42°, and Y-36° planes, respectively. The better mechanical properties and “plastic” removal mechanism of X-112° plane resulted in the lower value of MRR. Also, the much lower SRS corresponded well with the relatively less sensitivity of MRR with rotation speed on X-112° plane. Results of this study suggested that the plastic parameter of SRS could provide as an excellent indicator to bridge the machining response and intrinsic deformation mechanism for brittle single crystal ceramics.

Specific complex-oxide crystals with strong nonlinear absorption and nonlinear refraction as promising optical materials

In the present work the third-order nonlinear optical (NLO) properties of the complex-oxides crystals, including nonlinear absorption (NLA) and nonlinear refraction (NLR) are performed by the Z-scan technique. The non-centrosymmetric lithium niobate (LiNbO3) and lithium tantalite (LiTaO3) and centrosymmetric cadmium tungstate (CdWO4), calcium tungstate (CaWO4) and calcium molybdate (CaMoO4) single crystals were used for experimental investigation. The main nonlinear optical parameters, such as the two-photon absorption coefficient β, the nonlinear refractive index n2 and third-order nonlinear susceptibility for all investigated crystals are evaluated at different wavelengths λ: 1064 nm and 532 nm. Herein, the influence of λ and crystal orientation of third-order NLO properties on complex-oxides crystals is discussed.

Broadband infrared light source by simultaneous parametric down-conversion

Spontaneous parametric down-conversion is an essential tool for a quantum light source in the infrared region ranging 2–5 µm for the purpose of material identification, chemical analysis, and gas sensing. So far, photon pairs from the process in a nonlinear crystal have low tunability and a narrow spectral range because of the phase-matching condition. Here, we propose a novel type of spontaneous parametric down-conversion processes that overcomes these challenges, where two photon pairs are simultaneously produced in the visible and infrared regions in periodically poled stoichiometric lithium tantalite. It allows broadband and tunable generation of infrared photon pairs that can be employed as an alternative light source for quantum infrared spectroscopy.

Optically Guided Pyroelectric Manipulation of Water Droplet on a Superhydrophobic Surface.

Controlled droplet manipulation by light has tremendous technological potential. We report here a method based on photothermally induced pyroelectric effects that enables manipulation and maneuvering of a water droplet on a superhydrophobic surface fabricated on lithium tantalite (LiTaO3). In particular, we demonstrate that the pyroelectric charge distribution has an essential role in this process. Evenly distributed charges promote a rapid hydrophobic to hydrophilic transition featuring a very large water contact angle (WCA) change of ∼76.5° in air. This process becomes fully reversible in silicone oil. In contrast, the localized charge distribution induced by guided laser illumination leads to very different and versatile functionalities, including droplet shape control and motion manipulation. The influence of a saline solution is also investigated and compared to the deionized water droplet. The focusing effect of the water droplet, a phenomenon that widely exists in nature, is particularly of interest. Simple tuning of the laser incident angle results in droplet deformation, jetting, splitting, and guided motion. Potential applications, such as droplet pinning and transfer, are presented. This approach offers a wide range of versatile functionalities and ready controllability, including contactless, electrodeless, and precise spatial and fast temporal control, with tremendous potential for applications requiring remote droplet control.

A watt-level yellow random laser via single-pass frequency doubling of a random Raman fiber laser

We report a watt-level yellow random laser at 589 nm. The laser is generated by single-pass second harmonic generation of a half-open random Raman fiber laser at 1178 nm in a periodically poled stoichiometric lithium tantalite crystal. The major limitation on power scaling is the usual broad linewidth of random Raman fiber lasers. By counter pumping instead of common co-pumping, and using narrower fiber Bragg grating as the single mirror, the output spectrum of the 1178 nm random laser is greatly narrowed. As a result, up to 1.09 W 589 nm laser is obtained from a 10.1 W fundamental power with a conversion efficiency of 10.8%. The power and conversion efficiency are significantly improved compared to the previous report on frequency doubling of random Raman fiber laser.

Sinterability and Dielectric Properties of LiTaO3-Based Ceramics with Addition of CoO.

Lithium tantalite (LiTaO3) is a common piezoelectric and ferroelectric crystal, but the LiTaO3 polycrystalline ceramics have rarely been reported, and their refractory character presents difficulties in their fabrication. In this study, LiTaO3-based ceramics with different amounts of CoO were prepared by pressureless sintering at 1250 °C, and the effects of the amount of sintering aid on the sinterability, microstructure, and dielectric properties of the ceramics were investigated. The relative densities of the LiTaO3-based ceramics were significantly improved by the addition of CoO powder. The LiTaO3-based ceramics achieved the highest relative density (89.4%) and obtained a well-grained microstructure when the added amount of CoO was 5 wt.%. Only the LiTaO3 phase in the ceramics was observed, indicating that the ions Co diffused into the LiTaO3 lattices and mainly existed in two forms: Co2+ and Co3+. The effects of the added amount of CoO on the dielectric properties of the LiTaO3-based ceramics were studied thoroughly. Consequently, the dielectric constant was enhanced, and the dielectric loss decreased in the LiTaO3-based ceramics with the addition of CoO. The optimal value was obtained at 5 wt.% of CoO-added LiTaO3-based ceramics.

Microstructure and Electrical and Mechanical Properties of Lithium Tantalate Ceramics Synthesized by a Sol-Gel Method

LiTaO3 ceramics has been produced from a fine powder synthesized by a sol-gel method from a Li,Ta-containing citrate precursor, and its microstructure and mechanical and electrical properties have been studied. Young’s modulus and microhardness of the ceramic lithium tantalite have been determined. The critical stress intensity factor of mode I KIC, which is a criterion for the crack resistance of a material, has been evaluated, and the effective fracture energy of the LiTaO3 ceramics has been determined. The complex impedance dispersion Z*(ω) has been studied, and temperature dependences of dielectric constant and conductivity have been measured in the temperature range ~300–705 K, which is crucial for the acoustoelectronic applications of ceramic lithium tantalate. In the temperature range studied, the static conductivity and relaxation time of LiTaO3 ceramics have been determined. The charge transport activation enthalpies for various temperature ranges have been estimated.

Microstructure and dielectric properties of LiTaO3 ceramics with MnO2 addition fabricated by hot-pressing sintering

Lithium tantalite (LiTaO3) is an excellent single crystal, only a few studies focused on polycrystalline LiTaO3 ceramics, because it is difficult to sintering densification in fabrication process by common sintering. In this paper, LiTaO3 composite ceramics with added 3 wt% MnO2 were obtained by hot-pressing sintering at different temperatures from 1200 to 1350 °C. The sinterability, microstructure and dielectric properties of LiTaO3 ceramics fabricated at sintering temperatures were investigated. The relative density of the LiTaO3 ceramics was significantly enhanced as the sintering temperature increases first and then decreased. The LiTaO3 ceramics achieved the highest relative density (98.6%) and shown homogeneous microstructure when sintered at 1300 °C. The LiTaO3 and manganese oxide phases were observed in the MnO2/LiTaO3 ceramics fabricated at different sintering temperatures. The dielectric properties of MnO2/LiTaO3 ceramics were significantly influenced by the sintering temperatures. The study of dielectric properties revealed that the specimen had excellent dielectric properties when sintering temperature was 1300 °C and the dielectric constant was 78, as it tends to stay invariable at room temperature.

Effects of MnO2 addition on the microstructure and dielectric properties of LiTaO3 ceramics

Lithium tantalite (LiTaO3) is an excellent single crystal. At present, only a few research studies have focused on polycrystalline LiTaO3 ceramics because it is beset with difficulties for the fabrication of dense ceramic by conventional sintering. In this study, LiTaO3 composite ceramics with added different MnO2 contents were obtained by hot-pressing sintering at 1300 °C. The sinterability, microstructure, and dielectric properties of LiTaO3 composite ceramics were investigated. The relative densities of the LiTaO3 composite ceramics are remarkably improved by the addition of the MnO2 powder. The LiTaO3 ceramic achieves the highest relative density (98.6%) and exhibits a homogeneous microstructure following the addition of 3 wt% MnO2 sintered in N2. Only the LiTaO3 phase is observed at a MnO2 content addition below 3 wt%, and the secondary phase is found with further increases of added MnO2 (≥3 wt%) to the MnO2/LiTaO3 (MLT) composite ceramics. The dielectric properties of the MnO2/LiTaO3 composite ceramics are significantly influenced by the MnO2 contents, and the relatively optimal values are obtained when the addition of 3 wt% MnO2 sintered in N2.

Frequency Difference Thermally and Electrically Tunable Dual-Frequency Nd:YAG/LiTaO3 Microchip Laser

This study presents a dual-frequency microchip laser with a thermo-optically and electro-optically tuned frequency difference. The dual-frequency microchip cavity is formed by bonding a Lithium tantalite (LiTaO3, LTO) crystal chip and a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal chip. A single longitudinal mode is generated by the Nd:YAG crystal and split into two frequencies with perpendicular polarizations due to birefringent effect in the LTO chip. Furthermore, continuous beat frequency tuning at different scales is realized by adjusting the temperature and voltage applied to the LTO crystal. A maximum beat frequency of up to 27 GHz is obtained, and the frequency difference lock-in phenomenon is observed below the frequency difference of 405 MHz.

LITAO3 CHARACTERIZATION OF RUBIDIUM ON TEMPERATURE VARIATIONS

One of the studies that recently attracted the attention of physicists is research on ferroelectric material because this material is very promising for the development of new generation devices in connection with the unique properties it has. Ferroelectric materials, especially those based on a mixture of lithium tantalite (LiTaO3), are expected to be applied to the infrared sensor. Lithium tantalate (LiTaO3) is a ferroelectric material that is unique in terms of pyroelectric and piezoelectric properties that are integrated with good mechanical and chemical stability. Therefore LiTaO3 is often used for several applications such as electro-optical modulators and pyroelectric detectors. LiTaO3 is a non-hygroscopic crystal, colorless, soluble in water, has a high transmission rate and does not easily damage its optical properties. LiTaO3 is a material that has a high dielectric constant and a high load storage capacity. This research has succeeded in determining the band gap energy of the LiTaO3 film in the rubidium chamber obtained in the range of values 2.02-2.98 eV as shown in figure 4. The LiTaO3 film after the annealing process at a temperature of 650 oC, has the highest band gap energy of 2.98 eV. Large energy is needed on the electrons to be excited from the valence band to the conduction band. Whereas in the LiTaO3 film after an annealing process of 800 oC, the band gap energy obtained is 2.02 eV. This makes it easier for electrons to be excited from the valence band to the conduction band because the energy needed is not too large.