线性电介质和中心对称光折变晶体界面表面波的研究

报道了中心对称光折变晶体与线性电介质界面表面波的形成及能量变化. 通过调节传播常数和波导参数的方法,可以得到非局域、振荡、局域三种类型的表面波. 波导参数和传播常数之差大于阈值时,线性电介质和中心对称光折变晶体界面可以形成局域表面波. 波导参数为正值时,局域表面波主要聚集在中心对称光折变晶体内,随着传播常数的增大,波能量随之单调递增,表面波可以稳定传播. 在给定的条件下,调节决定非线性作用强度的可变参量可以控制局域表面波模的阶数和传播波形. 关键词： 非线性光学 中心对称光折变晶体 表面波     

光折变晶体钛酸秘的折射率和光学均匀性的测量

本文报导光折变晶体钛酸铋的折射率和光学均匀性的测量结果。     

在金属与光折变晶体界面形成的表面波研究

应用质点振荡模型和数值模拟方法研究了在金属与光折变晶体界面形成表面波的条件及其能量变化. 结果表明: 传播常数的正负影响表面波的类型及波能量分布, 当传播常数取负值时在界面处形成非局域表面波, 取正值时在界面处形成振荡表面波和局域表面波, 局域表面波的能量随传播常数的变大而单调递增. 在一给定的物理系统中, 可通过调节决定非线性效应强度的可变参量控制不同阶数局域表面波模及其传播波形.     

Azimuthal dependence of the two-photon absorption coefficient for CdP2 crystals with tetragonal syngony

We studied the two-photon absorption coefficient (β) for cadmium diphosphide (CdP₂) single crystals in the tetragonal modification vs. the polarization azimuth (φ) of the incident light for intensities close to the optical breakdown (or optical damage) threshold for the crystal (11 MW/cm²). We have established that the value of β_max = 0.16 cm/MW is reached for φ = 0, i.e., for the ordinary wave. At the lasing frequency of a ruby laser, β_⊥/β_|| = 2.13, which suggests anisotropy of the two-photon absorption in the studied crystals. These dependences are needed for design and fabrication of quantum electronics and nonlinear optics elements whose operation is based on the use of the two-photon absorption effect for high radiation fluxes. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 76, No. 1, pp. 117–121, January–February, 2009.     

利用两种响应时间不同的光折变晶体实现仅对物体变化部分成像

用两种响应时间相差很大的光折变晶体Ce:SBN和Fe:LiNbO_3作为相位共轭麦克尔逊干涉仪的两个相位共轭镜,得到同一物体的两个有时间差的相位共轭像,再对这两个像做实时“异或”运算,就能实现仅对物体随时间变化部分的成像.这种方法可以大大增加两相位共轭镜的响应时间差,具有最小可探测速度低,输出信号强、输出保持时间长的优点.文中对此作了理论分析,并提供了该系统对真实物体成像的实验结果.     

Interactions of dark solitons in photovoltaic photorefractive crystals with diffusion nonlinearity

We investigate the interaction of spatial dark optical soliton pair in open-circuit photovoltaic photorefractive crystals by considering the effect of background light and diffusion nonlinearity. We show that the spatial dark solitons repel each other and travel along different trajectories for the coherent interactions that one undergoes reflection and the other one deflects significantly when they are closely overlapped, and the dark solitons attract and deflect simultaneously along a parabolic trajectory for the case of incoherent interactions. The deflection distance depends on the intensities and the initial separation between the dark solitons.     

掺Yb钒酸盐晶体激光振荡中的光学双稳态现象研究

研究了三种掺Yb钒酸盐晶体Yb:LuVO4,Yb:YVO4和Yb:GdVO4的激光振荡中所呈现的光学双稳态效应.以晶体所吸收的抽运功率表征的双稳区宽度ΔPabs可超过1W,在双稳区高功率一侧的边界,即激光振荡的上阈值点,出现激光输出功率的不连续变化或跃变,同时发生亚毫秒时间尺度上的大幅度强度涨落.谐振腔的输出耦合透过率、晶体长度、晶体中的热效应等对双稳态效应均具有重要影响.     

648nm激光雪崩抽运掺Tm晶体的本征光学双稳特性研究

理论研究了648nm激光雪崩抽运掺Tm晶体的本征光学双稳态.根据系统的非线性速率方程理论,推导出了稳态近似下雪崩阈值的解析表达式,数值研究了光子雪崩动力学响应、本征光学双稳性以及系统参数对光学双稳态的影响等.研究结果表明,648nm激光抽运下可以观察到掺Tm激光晶体的2μm荧光辐射本征光学双稳态,通过改变可控的实验参数能够实现对光学双稳回线环的形状调节. 关键词： 光学双稳 动力学 掺Tm晶体 光子雪崩     

648nm激光雪崩抽运掺Tm晶体的本征光学双稳特性研究

理论研究了648nm激光雪崩抽运掺Tm晶体的本征光学双稳态.根据系统的非线性速率方程理论，推导出了稳态近似下雪崩阈值的解析表达式，数值研究了光子雪崩动力学响应、本征光学双稳性以及系统参数对光学双稳态的影响等.研究结果表明，648nm激光抽运下可以观察到掺Tm激光晶体的2μm荧光辐射本征光学双稳态，通过改变可控的实验参数能够实现对光学双稳回线环的形状调节.     

CRT－LCLV and photorefractive crystl BSO based real－time joint transform correlator

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基于粒子成像测速技术的水中气泡界面的光学性质研究

基于粒子成像测速的流体可视化技术，根据菲涅耳公式计算了入射到水中气泡界面的光强，得出点光源连续两次反射或折射的光强具有等比数列的规律，光线在气泡界面反射、折射4次就变成完全偏振光且光线几乎消失.当入射角避开35°左右时，即便有一定宽度的线光源入射到气泡界面，第2次折射出气泡的光强与线光源的宽度无关，类似一条光线入射所产生的光强，给出了面光源在界面所产生的光强的二重积分表达式.线光源所产生的界面光强理论值、面光源产生的光强数值解与实验值都较为符合. 关键词： 水中气泡 界面 光强 粒子成像测速     

Fabrication of large-area 3D photonic crystals using a holographic optical element

A holographic technique for fabricating 3D photonic crystal is presented. The key element in the fabrication system is a holographic optical element (HOE) consisting of three gratings. Used in combination with a mask, the HOE can generate four beams under single illuminating beam, and 3D lattice structures can be formed by the interference of the four beams. Holographic approach is used to make HOE, so large area lattice structures can be fabricated. Numerical simulations indicate that beam intensity ratio of central beam to outer beam is one of the factors that affects the structures fabricated in photoresist, and high diffraction efficiency of the gratings in HOE is favorable when using cw laser with relatively low power as light source. Experimental results show clear 3D lattice structures fabricated using the HOE, verifying the effectiveness of the technique.     

Localized surface waves at the interface between the linear dielectric and photorefractive medium with drift and diffusion nonlinearity

We consider the propagation of the laser beam near the interface between the linear dielectric and photorefractive medium with drift and diffusion nonlinearity. We demonstrated the possibility of the surface waves formation, found the profiles of such surface modes and investigated waveguiding properties of the dielectric-photorefractive medium boundary. The effective particle theory was used to derive an ordinary differential equation that describes the beam center trajectory during the reflection from the interface.     

Surface electromagnetic waves at the interface of photorefractive crystals with a drift-diffusion nonlinearity mechanism

Within the accuracy of the plane-wave approximation, a solution of the boundary-value problem for the Maxwell equations is obtained for surface electromagnetic waves at the interface between a photorefractive crystal and a transparent isotropic medium. It is shown that in this case, of all the kinds of surface waves, only soliton-type waves can be generated. Characteristic parameters of these waves are determined for a photorefractive SBN (strontium-barium-niobate) crystal.     

用电磁理论说明各向异性晶体的基本光学现象

用电磁理论说明各向异性晶体为什么会产生双折射,双折射的光为什么都是线偏振光.     

Crystal growth,structure and optical properties of Pr~(3+) -doped yttria-stabilized zirconia single crystals

The development of blue semiconductor light-emitting diodes(LEDs) has produced potential applications for Prdoped materials that can absorb blue light, especially crystals, and we now report structure and optical properties for high-quality Pr-doped single crystals of yttria-stabilized zirconia(YSZ) grown by the optical floating zone(FZ) method.X-ray diffraction(XRD) and Raman spectroscopy showed that all of the single crystal samples were in the cubic phase,whereas the corresponding ceramic samples contained a mixture of monoclinic and cubic phases. X-ray photoelectron spectroscopy(XPS) and electron paramagnetic resonance(EPR) spectroscopy showed that Pr was present as the Pr~(3+) ion in ceramic rods and single crystals after heating to high temperatures. The absorption and photoluminescence excitation(PLE) spectra of the Pr-doped YSZ crystals measured at room temperature showed strong absorption of blue light, while their photoluminescence(PL) spectra showed five emission peaks at 565 nm, 588 nm, 614 nm, 638 nm, and 716 nm under450 nm excitation. The optimum luminescence properties were obtained with the crystal prepared using 0.15 mol% Pr_6O_(11),and those with higher concentrations showed evidence of quenching of the luminescence properties. In addition, the color purity of Pr-doped YSZ single crystal reached 98.9% in the orange–red region.     

Subwavelength imaging through one-dimensional metallodielectric photonic crystals at optical frequencies

We present a study of mode characteristics of multilayer metal-dielectric (M-D) structure and use the Eigen mode expansion (EME) method to simulate the subwavelength imaging effect that can be realized at the designed position. We show that the quality of the image is affected not only by absorption but also the finite width of the layers. By proper design and considering the real losses, a super lens with a resolution of about λ₀/6 (λ₀ is the wavelength in the air) can be obtained. Our researches of this structure point to that a transparent material can be composed from non-transparent materials by alternatively stacking different materials of thin nanofilms, which also provide an opportunity to expand the exploration of the wave propagation in metals, both in the linear and nonlinear regimes.     

基于NOLF双稳效应对经DSF压缩后的超短光脉冲进行消基座

基于非线性FP腔（NOLF）双稳效应，提出一种利用掺铒光纤放大器（EDFA）及NOLF对经DSF压缩后的超短光脉冲进行消基座的方案.利用耦合模方程，分析了NOLF的消基座特性.结果表明，通过合理选择NOLF的反射率、入射脉冲的中心频率与NOLF的共振频率的失谐量及EDFA的增益，可使脉冲的基座能量比减小一半. 关键词： 超短光脉冲 消基座 非线性FP腔 光学双稳 掺铒光纤放大器     

光在两单轴晶体分界面的反射与透射系数

研究光在两单轴晶体分界面处的反射和折射情况,分析了反射光和折射光的振幅与相位,给出了光在两单轴晶体分界面处的反复和透射系数。     

Determination of the liquid crystals phase transition temperatures using optical rotation effect

Using optical rotation effect, a sensitive, simple optical analytical system is developed for determining the phase transition temperatures of liquid crystals (LCs). When a monochromatic polarized light passes through LCs sample and analyzer, the light intensity changes with temperature. Especially, during the phase transition process, the intensity varies greatly due to optical rotation effect. The variation of light intensity versus variation of temperature curve shows the phase transition temperatures of LCs clearly. The phase transition temperatures of three cholesteric liquid crystals (ChLCs) and a nematic liquid crystals (NLCs) were detected by this method, and compared with those of the differential scanning calorimetry (DSC) and polarized light microscope (PLM) methods.