共查询到20条相似文献,搜索用时 31 毫秒
1.
Qinglong Meng Bin Zhang Sencheng Zhong Liguo Zhu 《Applied Physics A: Materials Science & Processing》2016,122(6):582
The damage threshold of lithium niobate crystal under single and multiple femtosecond laser pulses has been studied theoretically and experimentally. Firstly, the model for the damage threshold prediction of crystal materials based on the improved rate equation has been proposed. Then, the experimental measure method of the damage threshold of crystal materials has been given in detail. On the basis, the variation of the damage threshold of lithium niobate crystal with the pulse duration has also been analyzed quantitatively. Finally, the damage threshold of lithium niobate crystal under multiple laser pulses has been measured and compared to the theoretical results. The results show that the transmittance of lithium niobate crystal is almost a constant when the laser pulse fluence is relative low, whereas it decreases linearly with the increase in the laser pulse fluence below the damage threshold. The damage threshold of lithium niobate crystal increases with the increase in the duration of the femtosecond laser pulse. And the damage threshold of lithium niobate crystal under multiple laser pulses is obviously lower than that irradiated by a single laser pulse. The theoretical data fall in good agreement with the experimental results. 相似文献
2.
The ridge waveguide fabrication with periodically poled MgO-doped lithium niobate for green laser 总被引:1,自引:0,他引:1
Ridge waveguides were fabricated using an external field, a precision lapping machine and neutron loop discharge (NLD) in magnesium-oxide-doped lithium niobate. The measured quasi-phase-matching (QPM) wavelength of the second-harmonic generation (SHG) in a 30 mm long periodically poled magnesium-doped lithium niobate (PPMgLN) ridge waveguide which has a domain period of 6.8 μm is about 532 nm. A fabricated periodically poled magnesium-doped lithium niobate ridge waveguide was duty cycle of 51.9 ± 2.83% and demonstrated second-harmonic generation. By using this periodically poled magnesium-doped lithium niobate ridge waveguide, highly effective, low-cost optical devices with high power or short wavelength can be achieved. 相似文献
3.
Michael Esseling Annamaria Zaltron Nicola Argiolas Giovanni Nava Jörg Imbrock Ilaria Cristiani Cinzia Sada Cornelia Denz 《Applied physics. B, Lasers and optics》2013,113(2):191-197
We investigate the applicability of highly reduced lithium niobate samples doped with iron for the use as optoelectronic tweezers. Increasing the reduction degree of Fe-doped lithium niobate is well known to increase the photoconductivity and reduce the writing time of internal space-charge fields. Based on our measurements of the photorefractive properties, we determine the optimal conditions for dielectrophoretic trapping and present the application of Fe-doped lithium niobate as optoelectronic tweezers. For higher reduction degrees, an unexpected decrease in the photovoltaic current density and the saturation space-charge field is reported. 相似文献
4.
Domas Paipulas Viačeslav Kudriašov Mangirdas Malinauskas Valerijus Smilgevičius Valdas Sirutkaitis 《Applied Physics A: Materials Science & Processing》2011,104(3):769-773
We report studies of the modifications induced inside lithium niobate and KDP crystals by Yb:KGW ultrafast laser pulses, having
300-fs pulse duration and operating at 100-kHz repetition rate. By focusing the laser beam with a 0.42 numerical-aperture
objective, we have recorded homogeneous volume Bragg gratings in the bulk of the niobate crystal that showed excellent diffraction
efficiencies, reaching up to 87%, and remained permanent after thermal annealing for one hour at 150°C. The refractive index
modification level was found to be 0.002 in lithium niobate. The results show that lithium niobate is a very promising crystal
candidate for microphotonics applications. On the contrary, in the KDP crystal no smoothly modified refractive index zones
were created. 相似文献
5.
《Ultrasonics》2013,53(1):185-190
Lithium niobate piezocomposites have been investigated as the active element in high temperature resistant ultrasonic transducers for non-destructive testing applications up to 400 °C. Compared to a single piece of lithium niobate crystal they demonstrate shorter pulse length by 3×, elimination of lateral modes, and resistance to cracking. In a 1–3 connectivity piezocomposite for high temperature use (200–400 °C), lithium niobate pillars are embedded in a matrix of flexible high temperature sealant or high temperature cement.In order to better understand the design principles and constraints for use of lithium niobate in piezocomposites experiments and modelling have been carried out. For this work the lithium niobate piezocomposites were investigated at room temperature so epoxy filler was used. 1–3 connectivity piezocomposite samples were prepared with z-cut lithium niobate, pillar width 0.3–0.6 mm, sample thickness 1–4 mm, pillar aspect ratio (pillar height/width) 3–6, volume fraction 30 and 45%. Operating frequency was 1–2 MHz.Experimental measurements of impedance magnitude and resonance frequency were compared with 3-D finite element modelling using PZFlex. Resonance frequencies were predicted within 0.05 MHz and impedance magnitude within 2–5% for samples with pillar aspect ratio ⩾3 for 45% volume fraction and pillar aspect ratio ⩾6 for 30% volume fraction. Laser vibrometry of pulse excitation of piezocomposite samples in air showed that the lithium niobate pillars and the epoxy filler moved in phase. Experiment and simulation showed that the thickness mode coupling coefficient kt of the piezocomposite was maintained at the lithium niobate bulk value of approximately 0.2 down to a volume fraction of 30%, consistent with calculations using the (Smith and Auld, 1991 [1]) model for piezocomposites. 相似文献
6.
7.
A number of anomalies are revealed in the temperature dependence of the primary pyroelectric coefficient for single-domain crystals of lithium niobate LiNbO3 in the temperature range 310–330 K. It is shown that these anomalies are associated with the transformation of the domain structure of the lithium niobate crystals. The problem regarding the correct performance of the pyroelectric measurements and the possible influence of the observed effects on the optical properties of lithium niobate crystals and on the recording of optical phase holograms are discussed. 相似文献
8.
Lithium niobate is praised as silicon in nonlinear optics for its wide usage both in fundamental science and applications
in optics. But its photorefractive effect hinders it from more extensive application in optics. The deadlock has been broken
by doping some metallic elements such as magnesium into the congruent lithium niobate crystal for its high damage resistance.
The single-shot and multi-shot surface ablation experiments by femotosecond laser with the wavelength of 800 nm and the duration
of 80 fs were conducted in the same condition and the ablation threshold fluence was gained for congruent lithium niobate
crystal and 6 mol % Mg-doped lithium niobate crystal. The band gap widening after doping is responsible for the discrepancy
of the ablation thresholds between the two samples. The laser threshold fluence dependence of lasershot number demonstrates
the difference of the accumulation effect. The large reduction of trapping cross section for electrons after heavy doping
of magnesium is focused more to interpret this distinction. 相似文献
9.
10.
A. K. Bandyopadhyay P. C. Ray V. Gopalan 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(4):525-531
Ferroelectric materials, such as lithium niobate, show interesting non-linear hysteresis behavior that can be explained by
a dynamical system analysis. By using variational principle, a non-linear Klein-Gordon (K-G) equation is derived for lithium
niobate type of uniaxial ferroelectrics involving various types of energy, which was not considered previously to construct
the Hamiltonian. This leads to soliton solutions under different conditions of soliton velocity. The critical value of the
(dimensional) effective electric field has been estimated to be 54–58 kV/cm for lithium niobate depending on the impurity
content in these type inhomogeneous ferroelectrics. Beyond this critical field, there is no existence of solitons. This critical
field is related to a break-up mechanism of Landau-Ginzburg two-well potential to a single well, as the driving force is increased. 相似文献
11.
We efficiently generated far-infrared radiation at the wavelengths centered at 20.8?μm in the vicinity of one of the polariton resonances of lithium niobate. Such an efficient nonlinear conversion is made possible by exploiting phase matching for difference-frequency generation in lithium niobate. The highest peak power reached 233?W. 相似文献
12.
An electric-field poling process was established that yielded uniform periodically poled lithium niobate (PPLN) in 0.5 mm
thick lithium niobate substrate. We have fabricated 50 mm long fanned as well as multigrating PPLNs having period variations
from 25 μm to 32 μm. These PPLNs are required for quasi-phase-matched (QPM) optical parametric oscillator (OPO) applications.
We have also configured a bench-top OPO set-up based on these PPLNs. 相似文献
13.
对LiNbO3: Fe晶体中二波耦合过程进行了动态观测.进一步探讨了LiNbO 3:Fe晶 体中弱光放大的物理机理.发现LiNbO3 : Fe晶体中二波耦合过程的弱光放大 对c轴指 向有明显的依赖关系,虽然光生伏打效应对光生载流子的迁移有主要贡献,但扩散机理的贡 献仍不可忽略.弱光最终得到放大是瞬态能量转移与扩散机理引起的能量转移的共同贡献.弱 光放大达到准稳态之后的下降过程为瞬态能量转移的时间指数衰减过程与光散射引起的能量 耗散的共同贡献.
关键词:
光折变效应
光放大
掺杂铌酸锂 相似文献
14.
The two photorefractive centres in iron doped nearly stoichiometric lithium niobate crystals 下载免费PDF全文
This paper investigates the photorefractive properties of iron doped lithium niobate with different [Li]/[Nb] ratios The experimental results show two photorefractive centres for iron doped near-stoichiometric lithium niobate crystal Besides Fe^2+ and Fe^3+ ions, small polarons and bipolarons are considered as another photoactive centre. 相似文献
15.
We report the numerical observation of discrete spatial solitons in a periodically poled lithium niobate waveguide array by applying an electrical field through electro-optical effect. We show that discrete spatial soliton can be controlled by applied voltage in the periodically poled lithium niobate. 相似文献
16.
The structure of lithium niobate single crystals is studied by a complex technique that combines scanning electron microscopy and atomic force microscopy. By implementing the piezoresponse force method on an atomic force microscope, the domain structure of lithium niobate crystals, which was not revealed without electron beam irradiation, is visualized 相似文献
17.
The impact of protons and copper on the dark conductivity of copper-doped photorefractive lithium niobate crystals is investigated
by observation of the dark decay of holograms. The dark conductivity is significantly smaller than that of iron-doped lithium
niobate. A non-mono-exponential hologram decay is observed, which needs to be considered for multiplexing of holograms.
Received: 25 March 2002 / Published online: 2 May 2002 相似文献
18.
Iron-doped lithium tantalate crystals are grown by the Czochralski method and their photorefractive properties are examined with holographic methods. Dynamic range, holographic sensitivity, photoconductivity, and dark storage time are measured in dependence on the iron concentration and light intensity. The largest refractive-index change for ordinarily polarized light is 3.5×10-4, in comparison with 6.2×10-4 for iron-doped lithium niobate. Due to a small mobility of protons the dark storage time of holograms in lithium tantalate is larger than that in lithium niobate. PACS 42.40.Pa; 42.70.Ln 相似文献
19.
J. Lamela D. Jaque A. Rodenas F. Jaque G. A. Torchia J. R. Vazquez C. Mendez L. Roso 《Applied Physics A: Materials Science & Processing》2008,93(1):177-181
Near-field-optical-microscopy has been used to study the micro-modifications caused by femtosecond laser pulses focused at
the surface and in the volume of lithium niobate crystals. We have found experimental evidence of the existence, close to
femtosecond ablation craters, of periodic modifications in the surface reflectivity. In addition, the potential application
of near-field-optical microscopy for the spatial location of permanent modifications caused by femtosecond pulses focused
inside lithium niobate crystals has been also demonstrated. 相似文献
20.
Youbao Wan Junhao Chu Shaoling Guo Lingxian Bo Tianyan Yu Bingkun Yu 《International Journal of Infrared and Millimeter Waves》2001,22(1):197-205
The potassium lithium niobate crystals have been grown up. The shapes of solid-melt interfaces which maintaining the steady growth of the potassium lithium niobate crystals have been described. The optical transmission spectrum of the crystal has been surveyed. The perfected crystals showed good Second Harmonic Generation properties. 相似文献