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Sb掺和对TeOx薄膜光学和静态记录特性的影响 总被引:2,自引:2,他引:0
以真空蒸镀法在K9玻璃基底上制备了TeOx:Sb单层薄膜,对薄膜的结构、光学和静态记录特性进行了研究.结果表明,Sb掺和后TeOx薄膜的结构、反射光谱和光学常量均发生了明显变化.TeOx:Sb薄膜具有良好的写入灵敏性并具有了一定的可擦除性能,该类薄膜有望作为可擦除光存储介质. 相似文献
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采用基于密度泛函理论的第一性原理方法, 对具有缺陷型黄铜矿结构的半导体材料AⅡAl2C4Ⅵ(A=Zn, Cd, Hg; C =S, Se)的构型和电子结构进行研究, 并系统考察了各晶体的光学性质. 对于线性光学性质, 五种晶体在红外区和部分可见光区具有良好的透光性能, 其中HgAl2S4和HgAl2Se4晶体具有适中的双折射率. 在非线性光学性质方面, 该类晶体倍频效应较强, 理论预测得到的二阶静态倍频系数均较大(>20 pm/V). 体系的倍频效应主要来源于价带顶附近以S/Se 价p轨道为主要成分的能带向含有较多Al/Hg 价p成分的空带之间的跃迁. 通过与已商业化的AgGaC2晶体光学性质的对比, 结果表明HgAl2S4和HgAl2Se4是一类性能优良的红外非线性光学晶体材料. 相似文献
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用传统的熔融急冷法制备了组分为(100-2x) GeS2-xGa2S3-xCsCl (x= 15, 20, 25 mol%)系列硫卤玻璃, 测试了样品玻璃的吸收光谱. 采用Z-扫描方法测试了样品的三阶非线性光学特性. 分析了激光光子能量与玻璃三阶非线性光学特性的关系,并研究了组分变化对玻璃的三阶非线性性能的影响. 研究结果表明,光子能量的少许改变可以使非线性吸收系数在一个较大的范围内变化,随着光子能量的增大, 玻璃的非线性吸收系数β 增大;当光子能量趋近于0.5Eg时, β值趋近于0,玻璃有最佳的品质因子; 玻璃样品中CsCl含量的增加使得玻璃的光学带隙Eg增大,短波截止边蓝移,非线性吸收系数β 减小. 但是由于结构与带隙对光学非线性的影响相反,非线性折射率γ 值变化不大. 该结果表明样品的光学非线性性能由光学带隙和结构两方面因素共同决定,对今后研究全光开关用硫系玻璃具有一定的指导意义和参考价值. 相似文献
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本文基于磁控溅射方法,功率从160 W增加到240 W,在石英衬底上沉积氧化铪薄膜(HfO2),并对沉积后的薄膜进行退火处理. 利用X射线衍射谱、X射线光电子能谱、紫外-可见-近红外透射谱和椭圆偏振仪对HfO2薄膜进行研究,对比了退火前后HfO2薄膜的光学特性及薄膜结构的变化. 实验结果显示,HfO2薄膜对波长大于200 nm的入射光具有很低的吸收系数. 优化退火温度和时间,可以将沉积后的HfO2薄膜从非晶态转化成多晶态. 退火有助于结晶生成和内应力的增加,同时退火可以优化薄膜的化学计量比,提升薄膜的光学密度及折射率. 对功率在220 W左右沉积的薄膜进行退火,获得的HfO2薄膜具有较高并且稳定的光学折射率(>2)和紫外光透射率,可在紫外波段减反膜系统中得到应用. 相似文献
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利用全固化单频Nd∶YVO4激光器抽运由periodically poled lithium niobate(PPLN)准相位匹配晶体组成的光学参量振荡器,通过调节晶体的温度,在信号模与闲置模近简并的情况下,完成了抽运场与两个亚谐波模在腔内同时共振,实现了光学参量振荡器的极低阈值运转(阈值为1.2mW);当抽运功率为阈值抽运功率的2.8倍时,观察到反射抽运光的正交位相压缩,压缩度达1.1dB.数值计算与实验结果一致 相似文献
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ECR-PECVD制备Si3N4薄膜的光学特性研究 总被引:1,自引:0,他引:1
本文研究了ECR-PECVD制备的Si3N4薄膜的光学特性.得到的Si3N4薄膜具有光致发光效应,在280℃沉积制备的Si3N4薄膜的光致发光波长为400nm,具有较好的单色性.测试分析了Si3N4薄膜对可见光、红外光具有较高的透射性能,Si3N4薄膜可作为红外光的增速减反射膜. 相似文献
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By use of the highly dispersive phase coupling effect in a photorefractive wave mixing process, we have observed ultraslow propagation of a single Gaussian light pulse with a group velocity ∼0.5 m/s in a photorefractive Bi12SiO20 crystal at room temperature. The ultraslow Gaussian pulse is amplified due to an intensity coupling effect but keeping its Gaussian profile with high fidelity. The group velocity of the Gaussian pulse can be controlled to a large extent. This technique is useful for controllable optical delay lines. 相似文献
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In the photorefractive wave-mixing system, fluctuation in the signal beam intensity of the photorefractive output with a reflection grating has been analyzed by employing pump feedback method. In this method, fluctuations of the photorefractive wave-mixing process not only induce the intensity fluctuation of the mixing waves but also induce phase fluctuation of the mixing waves. Thus, the phase of the pump and signal beams at the output surface fluctuates in time around a mean value. Using such a positive feedback method of a pump beams, the relative fluctuation in the photorefractive output signal beam intensity with respect to its mean intensity can be minimized significantly without reducing its mean intensity. The factors that control the fluctuation in the signal beam intensity, such as the phase fluctuation of the output pump beam, absorption strength of the material and the feedback reflectivity of the cavity mirrors, on the relative fluctuation of the output signal intensity in the photorefractive wave-mixing systems have been studied in detail. It has been found that the fluctuation of the output signal intensity relative to its mean intensity in the photorefractive wave-mixing system can be suppressed to larger extent by taking lower value of feedback reflectivity of the cavity mirrors which could exist at a higher value of absorption strength of the photorefractive materials. 相似文献
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Atsushi Okamoto Satoshi Honma Shunsuke Uemura Terumasa Ito 《Optics & Laser Technology》2007,39(4):881-884
This paper presents a new proposal for a mutually pumped phase conjugate mirror (MPPCM) using cross polarization. In the cross polarized MPPCM, two light beams, whose polarizations are orthogonal to each other, incident on a photorefractive crystal, causing photorefractive interaction to generate phase conjugate waves with an orthogonal polarization to an incident beam. The use of Ar+ laser and BaTiO3 crystal in an experiment for the cross polarized MPPCM found that diffraction efficiency for an extraordinary beam is about 20%. As opposed to a conventional parallel polarized MPPCM in which the use of a beam splitter is required to separate a diffraction beam, the cross polarized MPPCM can efficiently extract phase conjugate waves by means of a polarized beam splitter, demonstrating the advantage of substantially improved efficiency. 相似文献
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首次报道一种利用光折变晶体的光感应自泵浦实现图象色彩转换的方法。用此方法可得到具有相位共轭的正转换图象,其分辩率可达到281p/mm,同样的方法可用于将非相干图象转换成相干图象。 相似文献
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N.I. Nazhestkina A.A. Kamshilin O.V. Kobozev V.V. Prokofiev T. Jääskeläinen 《Applied physics. B, Lasers and optics》2001,72(6):767-773
Two-wave mixing of phase-modulated beams in photorefractive crystals under a dc electric field is studied both theoretically
and experimentally. Based on the vectorial theory of light diffraction in crystals of cubic symmetry, we derived an analytical
expression that describes the phase demodulation in crystals with an arbitrarily oriented electric field. The phase-demodulation
technique was used for estimation of the space-charge field created in photorefractive crystals. It is shown that the space-charge-field
grating created in GaP and Bi12TiO20 crystals is much smaller than that predicted from the one-level band-transport model of the photorefractive effect.
Received: 12 December 2000 / Revised version: 8 February 2001 / Published online: 27 April 2001 相似文献
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M. Imlau S. Haussühl T. Woike R. Schieder V. Angelov R.A. Rupp K. Schwarz 《Applied physics. B, Lasers and optics》1999,68(5):877-885
Elementary holographic phase gratings can be written in single crystals of Na2[Fe(CN)5NO]·2H2O, sodiumnitroprusside, by excitation of metastable electronic states in the blue–green spectral range. For light polarized
parallel to the crystallographic a and b axes of the orthorhombic crystal the light-induced modulation of the refractive index
reaches Δn≈2×10-3 at λ=514.5 nm. Although the largest population of the metastable states is reached for light polarized parallel to the crystallographic
c axis, a photorefractive response is not observed. In contrast to electro-optic photorefractive materials the photorefractive
effect depends mono-exponentially on the exposure and on the modulation of the incident light interference pattern. Beam-coupling
experiments demonstrate that written gratings are in phase with the interference pattern in correspondence with the fact that
the excitation of the metastable electronic states is local. The width of the rocking curve shows that the holographic gratings
are written completely over the volume of the crystal. Variations of the wavelengths within the excitation range as well as
of the crystal thickness do not influence the maximum photorefractive response. Investigations on the grating vector of the
written gratings show unambiguously that charge migration is not responsible for the photorefractive effect.
Received: 18 November 1998 / Revised version: 26 January 1999 / Published online: 12 April 1999 相似文献
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It is shown that under uniform illumination and application of an external electric field, a phase volume hologram in a photorefractive crystal exists in the form of relaxing running wave. Effective recording of such a running hologram is possible only by an interference pattern moving synchronously with the recorded grating. The physical nature of this phenomenon, the possible enhancement of the hologram diffraction efficiency upon recording of a running pattern and the main factors limiting its value are discussed for the case of photorefractive Bi12SiO20 crystals. 相似文献
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Light-induced scattering in photorefractive crystals 总被引:1,自引:0,他引:1
Light-induced scattering features in LiNbO3- and BaTiO3-crytals are compared with theories on holographic writing in photorefractive crystals. It is shown that they describe the experimental facts concerning the expected main scattering directions for a given incident polarization, the time development, the thickness and the wavelength dependence. Time records of the transmission offer a useful alternative for the determination of the photoconductivity. Furthermore, a new method for birefringence measurements is established. The high accuracy of this method is based on the automatic fulfillment of a phase matching condition by the anisotropically scattered radiation. 相似文献