共查询到20条相似文献,搜索用时 104 毫秒
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基于在539.75nm,632.8nm,1079.5nm,1341.4nm波长上和288K,338K,383K,423K温度条件下,对掺5mol%MgO和0.2mol%Ti的LiNbO3晶体的主折射率的精密测量,根据对LiNbO3晶体适用的修正的Sellmeier's方程,以解出参数Ci表达式的方法,求出上述温度时Sell-meier's方程的参数Ai,Bi,Ci,Di,以最小二乘法精确地拟合上述参数对温度T的线性关系,进而推导出这种晶体的折射率温度系数的表示式。利用此表示式可以计算波长在539.75nm~1341.4nm区间附近,温度在288K~423K范围左右Ti:Mg:LiNbO3晶体的折射率温度系数。为检验该折射率温度系数表示式的实用性,利用此表示式计算1079.5nm为基波的该晶体的二倍频非临界相位匹配温度,与实验值之差在1K以内,从而证明这个折射率温度系数表示式对于采用Ti:Mg:LiNbO3,晶体设计非线性光学器件是适用的。 相似文献
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The UV photorefractive properties of near-stoichiometric LiNbO3 single crystal are found to be significantly enhanced compared with the congruent one at 325 nm. The temperature dependence of the band edge of near-stoichiometric LiNbO3 crystal is investigated. Significant thermal-induced spectral shift in band gap which obeys the Bose-Einstein expression is observed, and the fundamental band gap at zero absolute temperature is found to be much larger than the congruent one. New absorption bands near the UV band edge which are much stronger in the near-stoichiometric LiNbO3 than those in the congruent LiNbO3 crystal show up at temperatures lower than ~400 K. Note that the UV photorefractivity is enhanced in SLN, which has exactly the same tendency as the absorption strength. 相似文献
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由材料参数测试和器件响应率测试证实,LiNbO3晶体的热释电响应率优值Mv为一般公认值的二倍。而且当温度升高时,Mv缓慢降低,并不出现某些文献所预示的明显增加。着重研究了LiNbO3探测器在高功率密度连续激光辐照下的输出特性。研究结果表明,在相同条件下,LiNbO3探测器的输出开始偏离线性所对应的最大功率密度远高于LiTaO3。仔细测定了LiNbO3晶体的固有介质损耗,并据此估计LiNbO3器件探测率的极限值。分析表明,就制备背景限探测率的器件的潜力而言,LiNbO3不低于TGS。 相似文献
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采用气相输运平衡技术,对不同掺镁浓度的铌酸锂进行了近化学计量处理,并检验了其抗光折变性能。实验结果表明,掺摩尔分数为2%的镁的近化学计量铌酸锂晶体,光折变阈值比同成分晶体提高了4个量级。通过施加4.5kV/mm的脉冲电场,在上述1.0mm厚z切晶体上制备出了周期为6.8μm的均匀畴结构。采用声光调Q Nd:YAG激光器作抽运光源,基频光波波长为1.064μm,平均输入功率为230mW,在室温条件下,得到波长为0.532μm,输出功率为2.8mW的倍频绿光输出,倍频转换效率为1.22%。。 相似文献
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Kodo Kawase Shingo Ichino Koji Suizu Takayuki Shibuya 《Journal of Infrared, Millimeter and Terahertz Waves》2011,32(10):1168-1177
Nonlinear optical terahertz wave generation is a promising method for realizing a practical source with wide frequency range
and high peak power. Unfortunately, many nonlinear crystals have a strong absorption in the terahertz frequency region. This
limits efficient and widely tunable terahertz wave generation. The Cherenkov phase-matching method is one of the most promising
techniques for overcoming these problems. We propose a prism-coupled Cherenkov phase-matching method, in which a prism with
a suitable refractive index at terahertz frequencies is coupled to a nonlinear crystal. We demonstrate prism-coupled Cherenkov
phase-matching terahertz generation using the DAST and LiNbO3 crystals. With a DAST crystal, we obtain a spectral flat tunability up to 10 THz by difference frequency generation. With
a LiNbO3 crystal, we observe a spectral flat broadband terahertz pulse generation up to 5 THz pumped by a femto second fiber laser.
The obtained temporal waveform is an ideal half cycle pulse suitable for reflection terahertz tomography. 相似文献
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Sen-Cheng Zhong Li-Guo Zhu Shi-Xing Tao Kun Meng Long-Yao Peng Qiao Liu Qi-Xian Peng Jian-Heng Zhao Ze-Ren Li 《Journal of Infrared, Millimeter and Terahertz Waves》2014,35(3):318-324
Optical rectification of laser pulses in LiNbO3 by tilted-pulse-front pumping(TPFP) is a powerful way to generate terahertz(THz) pulses. However, comprehensive theoretical analysis is still lack. In this work, we first established and presented a detailed theoretical model for TPFP scheme, which then was used to analyze the pump beam polarization dependent terahertz pulses generated by this scheme. The terahertz pulses polarization and generation efficiency for various pump beam polarization angle were investigated by using nonlinear susceptibility tensor of LiNbO3 crystal. The results indicate that one can change the polarization state of the terahertz pulse by changing the pump beam polarization. 相似文献
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Using piezoelectric LiNbO3 crystal oscillator method at 200 kHz, we have measured internal friction and modulus of YBa2Cu3O6+x short wires with 1 mm-diameter and about 5mm length under in situ cyclic heating-cooling treatment at temperatures of 300–1020K.
Polycrystalline YBa2Cu3O6+x wires show anelastic behavior as well as orthorhombic-to-tetragonal (O-T) phase transition within present temperature range.
There appears a strong internal friction peak below the O-T transition temperature, corresponding to the atomic site relaxation
between oxygen and a vacancy in the Cu-O plane of oxygen defective YBa2Cu3O6+x. A novel peak is observed after the cyclic heat treatments at around 700K. This relaxation is attributed to the hopping movement
of oxygen in the defective local structure of YBa2Cu3O6+x. 相似文献
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Kodo Kawase Manabu Sato Tetsuo Taniuchi Hiromasa Ito 《Journal of Infrared, Millimeter and Terahertz Waves》1996,17(11):1839-1849
Wide tunable terahertz (THz) wave generation was successfully demonstrated utilizing a grating coupler fabricated on the surface of a LiNbO3 crystal which was pumped by a Q-switched Nd:YAG laser. In this paper, we report the detailed characteristics of the oscillation and the radiation including tunability, spatial and temporal coherency, directivity, and efficiency. Oscillation using a LiTaO3 crystal was also performed, in which experimental phasematching condition values agreed well with the calculated one. 相似文献
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Hiroaki Minamide Shin’ichiro Hayashi Koji Nawata Takunori Taira Jun-ichi Shikata Kodo Kawase 《Journal of Infrared, Millimeter and Terahertz Waves》2014,35(1):25-37
Intense Terahertz (THz)-wave generation and highly sensitive THz-wave detection were obtained by wavelength conversion with nonlinear optical susceptibility χ(2) of LiNbO3 crystals. Maximum peak output of about 50 kW (5 μJ/pulse) was demonstrated in an injection-seeded THz-wave parametric generator pumped by post-amplified emission from a microchip Nd:YAG laser. Using the sub-nanosecond pulse duration of the laser proposed herein provides effective mitigation of stimulated Brillouin scattering in LiNbO3, producing higher gain for wavelength conversion between near-infrared (near-IR) pump light and THz waves. Monochromatic THz radiation was obtained in the continuous tuning range of 0.7–2.9 THz. Additionally, highly sensitive THz-wave detection was demonstrated based on up-conversion from THz waves to near-IR light as well as efficient THz-wave generation. The signal generated with non-collinear phase-matching condition showed spectroscopic detection on the screen apart from the LiNbO3 crystal. Highly sensitive detection with minimum energy of about 80 aJ/pulse (0.8 μW at peak) and a large dynamic range of more than 100 dB were achieved in this experiment. 相似文献
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DIAO Shu-yan YAO Jian-quan ZHENG Yi 《光电子快报》2006,2(4):269-272
Pulsed optical parametric generators(OPGs)and op-tical parametric oscillators(OPOs)have beenextensive-ly studied and developedfor generatingtunable coherentsources[1-5]that cover the wide spectral range fromthenear UVto the mid IR.In this letter we report… 相似文献
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The nonmagnetic element Ca-doped LiNbO3 films were prepared on Si (111) substrates by radio frequency (RF) mag- netron sputtering technique. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicate that the Ca atoms enter the LiNbO_3 lattice in the form of Ca^2+ ions. Superconducting quantum interference device (SQUID) resuits show that the Ca-doped LiNbO_3 films have room-temperature ferromagnetism and a maximum saturation magnetization of 4800 A/m at the 3% of Ca atom doping concentration. The room temperature ferromagnetism of the Ca-doped LiNbO_3 films can be attributed to the occurrence of vacancies due to Ca doping and is the intrinsic property. 相似文献
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Novel applications of photorefractive effect to optical signal processing are proposed and demonstrated. The applications of two-wave mixing (2-WM) in a bulk photorefractive crystal include logic operations and cross connect. Photorefractive crystal waveguide (PCW) is another primary concern. Holographic storage of Fourier transformed image in PCW and its application to optical neural network, two-dimensional array of PCW as a storage device, phase conjugate mirror using PCW, and structural consideration of PCW for efficient 2-WM are investigated. In the experiments,LiNbO
3 andBaTiO
3 waveguides are used.BaTiO
3 waveguide will be tested here for the first time. In a long-term prospect, all these technologies will eventually find important roles in optical signal processing. 相似文献
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Surface acoustic-wave (SAW) oscillators have advantageous features compared with other technologies. The Y-128° LiNbO3 is a well-known, high electromechanical-coupling SAW material, but its usefulness is limited because of its poor temperature-stability
property. The AlN films have some excellent characteristics, such as high SAW velocity, stable chemical properties, and high-temperature
stability. In this research, different thickness AlN films were sputtered on Y-128° LiNbO3 to be a composite substrate for the SAW oscillator. As AlN film thickness increased, the temperature coefficient of frequency
(TCF) value of the oscillator varied from −76.32 ppm/°C to −28.81 ppm/°C giving an improvement in the TCF of 62.25%. The oscillator
frequency at 25°C also varied from 40.0909 MHz to 41.6221 MHz, giving an improvement in the oscillator frequency of 3.8%.
The composite substrate (AlN/Y-128° LiNbO3) can enhance the oscillator frequency and effectively improve the poor temperature stability for the SAW oscillator. 相似文献
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光学限制器是光学系统的保护装置,其保护特性 是由光限制材料与光强或功率有关 的光学非线性效应所产生的,其中光折变晶体中的光感生散射便为该效应之一,多年来受到 世界研究者的广泛研究和关注。对于这类光感生散射,有人提出它是由晶体的表面和体散射 产生的,研究使用的晶体为 LiNbO3:Fe、LiTaO3、BaTiO3,并使用固定的晶体样品和 聚焦透 镜间距。为了进一步探索该散射的产生机理,本文研究了掺铁铌酸钾晶体在激光照射下产生 的光感生各向异性散射特性,利用Z扫描技术测量了该晶体中的 光感生折射率变化,并对晶 体中光散射形成的光学限制特性进行了研究。分析表明该各向异性散射主要是由掺铁铌酸钾 晶体中光感生的柱面透镜效应所导致的。利用光折变晶体中光感生光散射效应的光学限制器 ,一方面可以通过改变晶体尺寸、透镜焦距、小孔光阑大小等来调整其性质,另一方面因其 利用的是低功率连续波激光进行工作,所以能够承受更大的功率和更长的寿命。 相似文献
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C. Restoin C. Darraud-Taupiac J. L. Decossas J. C. Vareille J. Hauden 《Materials Science in Semiconductor Processing》2000,3(5-6)
In the field of integrated optics for WDM networks, periodically poled Ti:LiNbO3 seems to be an attractive candidate as it allows to build polarization-independent devices. A preliminary study about LiNbO3 without any Ti-indiffusion is presented here. Hence, a ferroelectric-inverted grating is achieved using electron beam (EB) on LiNbO3. In this study, the EB irradiation is performed with a scanning electron microscope (SEM) featuring a maximum accelerating voltage of 30 kV. A specific computer-aided design (CAD) application driving the SEM allows to write different structures such as periodic gratings. The EB domain-reversal method seems to be promising because of the accurate control and resolution of the reversed domains it can create. A pertinent choice of the irradiation conditions (accelerating voltage, probe current, scanning velocity, etc.) permits to generate gratings with 6.6, 20 and 30 μm wide periods. The inversion patterns have been revealed by HF-etching: domain walls are perpendicular to the surface in the first microns beneath the surface and their depth is almost the whole thickness of the wafer. 相似文献