Optical Bistability in Multimode Systems with Second-and Third-order Dispersive Nonlinearity

Mutual optical bistability is found for several modes in open cavities containing second- or third-order nonlinear materials. The quantum-statistical treatment yields the Fokker-Planck equation for any system of damped boson modes. Under certain conditions it is possible to state the extrema of the steady solution of the Fokker-Planck equation. They are compared with the steady states resulting from the classical deterministic treatment. In some cases both statements coincide.     

Nonlinear Optical Characteristics of C60 Thin Films

Abstract

The results of investigation of the real and imaginary parts of third‐order nonlinear susceptibility (χ⁽³⁾) of C₆₀ thin films (～100 nm) at the wavelength of Nd: YAG laser radiation (532 nm, τ = 55 ps) are presented using Z‐scan technique. Our studies show that the sign of Reχ⁽³⁾ changes from negative, at pulse repetition rate of 2 Hz to positive, at 0.5 Hz. Sign variations of the real part of the third‐order susceptibility were attributed to the influence of the thermal lens.     

原子层沉积技术及其在光学薄膜中的应用

回顾了原子层沉积(ALD)技术的发展背景,通过分析ALD的基本工艺,并与传统薄膜制备工艺进行了对比研究.介绍了它在膜层的均匀性、保形性以及膜厚控制能力等方面的优势.着重列举ALD在减反膜、紫外截止膜、折射率可调的薄膜、抗激光损伤薄膜及复杂结构光子晶体等方面的应用.同时指出了目前ALD工艺在光学薄膜应用中存在的主要问题,并对ALD未来的发展进行了展望.     

Evolution of Coherent States in a Dispersionless Fibre with Saturable Nonlinearity and the Generation of Macroscopic Quantum-superposition States

Abstract

We study the evolution of a initially coherent state of an electromagnetic field propagating in a Kerr medium with saturable nonlinearity. By using the quantum phase distribution formalism, we analyse the dependence of the output signal phase configuration upon input field amplitude. We observe that the saturation of the nonlinear contribution of the refractive index of the propagation medium introduces interference effects that compromise the observation of macroscopically well distinguishable components of the output state. For input amplitudes much larger than a characteristic saturation amplitude the final state differs from the input state only by an overall phase shift. Possible relevance of the present results in the experimental search of Schrödinger cat-like states using semiconductor-doped glass optical fibres is discussed.     

An Examination of the Nature of Propagating Optical Modes in a Thin Liquid-crystal Layer

Abstract

The optical modes excited in a thin homogeneous liquid-crystal layer are found to exist at momenta closely related to the pure eigenmodes of a simple uniaxial slab. However, when the electric field vectors within the liquid-crystal layer are examined, they demonstrate that the modes are not the simple pure orthogonalized eigenmodes. Furthermore, when an idealized three-media system is modelled to eliminate the influence of external fields, the same results apply. These results are attributable to the presence of boundaries.     

Experimental Observation of Thermo-optic Nonlinearity with a Long-range Surface Wave Supported by a Very Thin Palladium Film

Abstract

Using the attenuated total refiection technique a long-range surface exciton-polariton supported by a thin palladium film has been studied with 514·5 nm radiation. Thermo-optic nonlinearity is observed using both angle-scanning and radiation intensity-scanning at several fixed angles of incidence. Strong nonlinear effects are observed which may only be interpreted through a combination of photo-thermal displacement of the thin coupling gap and thermally induced index changes in the fluid that fills the gap. All the data obtained are adequately fitted by a model that incorporates both these effects.     

Nonlinear Optical Diagnostics of Thin Polycrystalline Lead Zirconate Titanate Films

Technical Physics Letters - Nonlinear optical microscopy techniques have been used to study thin films of single-phase (perovskite) and two-phase (perovskite–pyrochlore) lead zirconate...     

介孔Au/ZrO2复合薄膜的制备及其三阶非线性光学性能（英文）

以尿素为沉淀剂,通过沉积沉淀的方法,制备了高分散的金纳米颗粒负载的介孔氧化锆薄膜;以1064 nm激光为入射光束,通过Z扫描实验测试了复合薄膜的非线性光学折射和吸收,并计算了复合薄膜的非共振三阶非线性光学极化率(~10-10esu),金纳米颗粒的高分散性和氧化锆薄膜衬底的高线性折射率使复合薄膜显示了增强的三阶非线性极化率.     

Propagation of Gaussian Schell-model Beams in Dispersive and Absorbing Media

Abstract

The spectral properties and the coherence properties of Gaussian Schell-model beams, propagating in dispersive and absorbing media, are discussed. Unlike in free space, the ratio of the transverse spectral correlation length to the beam width is found to increase on propagation. Consequently upon propagation the beam becomes spatially more coherent at each frequency. Numerical results for the spectrum and for the degrees of spectral and of temporal coherence of the field are presented for some selected values of the beam parameters and for several values of the propagation distance. Propagation in a gain medium is also briefly discussed.     

非线性光学活性分子的线性电光效应

报道了反射型电光调制法研究６种偶氮化合物的线性电光效应,分析了给体－受体强度、掺杂浓度对线性电光系数的影响。结果表明,掺杂偶氮化合物４－「２－羟乙基苯甲氨基」－４－硝基偶氮苯的极化聚合物薄膜具有较强的线性电光效应,其线性电光系数随参杂浓度的增大而增大。     

非线性光学聚合物薄膜DCDHF-2-V/PMMA的特性

将新型有机非线性光学分子DCDHF-2-V按一定比例掺入聚甲基丙烯酸甲酯(PMMA)中,采用旋涂方法制备聚合物薄膜。为了得到宏观二阶非线性光学特性,在90℃对薄膜进行电晕极化,形成各向异性。对极化前后的薄膜进行紫外/可见光吸收频谱分析和原子力显微镜分析。采用RHF方法在6-31G基组上对DCDHF-2-V/PMMA薄膜体系中的DCDHF-2-V分子和PMMA进行闭壳层Hartree-Fock理论计算,得到它们的一阶超极化率β分别为60.278755×10-30esu和10.902267×10-34esu。     

连续式离子层吸附与反应法沉积CuSCN薄膜及其微观结构、光学特性研究

采用乙二醇作溶剂,以连续式离子层吸附与反应法(SILAR)实现硫氰酸亚铜(CuSCN)薄膜在ITO、TiO2薄膜以及玻璃衬底上的沉积.通过X射线衍射、扫描电镜和紫外-可见光透过谱等手段表征薄膜结晶性、表面和断面微观形貌以及光学特性.结果表明,衬底以及溶剂性质均对SILAR法薄膜沉积过程存在重要影响.ITO衬底上获得的CuSCN薄膜更为致密,呈结晶态,而TiO2薄膜衬底上的CuSCN薄膜主要由颗粒组成,为非晶态.随沉积次数增加,薄膜表面粗糙度增大,光学透过率逐渐下降.在优化条件下(ITO衬底,20次沉积循环),所得CuSCN薄膜表面致密均匀,可见光透过率约60%.     

有任意脱层复合材料梁的非线性动力稳定性

基于弹性理论建立了有脱层复合材料梁的基本方程式，研究了有任意脱层的考虑横向剪切变形的复合材料梁的非线性动力稳定性，对脱层梁进行分区处理，方便地描述了脱层长度，脱层位置，利用振型函数作为位移函数的形函数，采用增量谐波平衡法对基本方程式进行求解，考虑了不同脱层位置和不同脱层长度对脱层梁的非线性动力稳定性的影响，得出了各种情况下的动力不稳定性区域。     

Analysis of Modulational Instability in Monomode Optical Fibres with High-order Nonlinearity

Abstract

The modulational instability (MI) in monomode optical fibres with fifth-order nonlinearity, fibre loss, higher-order dispersion, and the temporal variation of third-order nonlinearity is studied theoretically. The conditions for the existence of the MI and the maximal modulational growth are given and discussed in detail. The results obtained show that the key factor dominating the producing condition of the MI is the power P of the continuous wave initially launched into the optical fibres. If P falls into 3/10<P/P ₀ <1/2 where P ₀ is defined as characteristic power, the MI can be produced in the range of not only anomalous group velocity dispersion but also the normal in which the final evolution state of the modulated wave is dark soliton.     

Motion of a Thin Oblique Layer of a Pseudoplastic Fluid

Motion of a thin layer of the Williamson fluid over an inclined solid surface in the gravitational field is considered. Expressions are obtained for the stationary motion of the film in the gravitation field. The influence of the latter and tangential vibrations of the solid surface on the flow in the layer is analyzed. It is shown that the vibrations generate a pronounced averaged fluid flow even in the weak gravitational field in which the film is at rest in the absence of vibrations. The effect of the nonmonotonic dependence of the mean flow velocity of the film on the vibration frequency of the surface is found.     

Size‐Dependent Nonlinear Optical Properties of Atomically Thin Transition Metal Dichalcogenide Nanosheets

Size‐dependent nonlinear optical properties of modification‐free transition metal dichalcogenide (TMD) nanosheets are reported, including MoS₂, WS₂, and NbSe₂. Firstly, a gradient centrifugation method is demonstrated to separate the TMD nanosheets into different sizes. The successful size separation allows the study of size‐dependent nonlinear optical properties of nanoscale TMD materials for the first time. Z‐scan measurements indicate that the dispersion of MoS₂ and WS₂ nanosheets that are 50–60 nm thick leads to reverse saturable absorption (RSA), which is in contrast to the saturable absorption (SA) seen in the thicker samples. Moreover, the NbSe₂ nanosheets show no size‐dependent effects because of their metallic nature. The mechanism behind the size‐dependent nonlinear optical properties of the semiconductive TMD nanosheets is revealed by transient transmission spectra measurements.