All-optical switching and nonlinear optical properties of HBT in ethanol solution

This paper demonstrates an all-optical switching model system comprising a single pulsed pump beam at 355 nm and a CW He-Ne signal beam at 632.8 nm with 2-（2＇-hydroxyphenyl）benzothiazole （HBT） in ethanol solution. The origins of the optical switching effect were discussed. By the study of nonlinear optical properties for HBT in ethanol solvent, this paper verified that the excited-state intramolecular proton transfer （ESIPT） effect of HBT and the thermal effect of solvent worked on quite different time scales and together induced the change of the refractive index of HBT solution, leading to the signal beam deflection. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitive optical switching devices.

Influence of Waveguide Properties on Wave Prototypes Likely to Accompany the Dynamics of Four-Wave Mixing in Optical Fibers

In this article, we study the impacts of nonlinearity and dispersion on signals likely to propagate in the context of the dynamics of four-wave mixing. Thus, we use an indirect resolution technique based on the use of the iB-function to first decouple the nonlinear partial differential equations that govern the propagation dynamics in this case, and subsequently solve them to propose some prototype solutions. These analytical solutions have been obtained;we check the impact of nonlinearity and dispersion. The interest of this work lies not only in the resolution of the partial differential equations that govern the dynamics of wave propagation in this case since these equations not at all easy to integrate analytically and their analytical solutions are very rare, in other words, we propose analytically the solutions of the nonlinear coupled partial differential equations which govern the dynamics of four-wave mixing in optical fibers. Beyond the physical interest of this work, there is also an appreciable mathematical interest.

Nonlinear Optical Properties, Optical Limiting and Optical Switching of Ag Nanoparticles Prepared by a Green Synthetic Method

Silver nanoparticles were synthesized using an aqueous extract of cinnamon berks (cinnamon cassia) as a reducer and stabilizer. The synthesized silver nanoparticles were characterized using UV-Vis spectrometry and Transmission Electron Microscopy (TEM), which revealed the nano nature of the particles. Nonlinear absorption and nonlinear refraction were measured using a Z-scan technique at different wavelengths with CW lasers. The third order nonlinear susceptibility was found to be between (1.5 to 22) ×10-14 m2/V2. The nonlinear property of the synthesized silver nanoparticles was used to demonstrate optical limiting and all-optical switching. An optical limiting threshold was found to be 0.1 mW at 632.8 nm.

Optical properties and local structure of Dy^(3+)-doped chalcogenide and chalcohalide glasses

Dy^3＋-doped Ge-Ga-Se chalcogenide glasses and GeSe2-Ga2Se3-CsI chalcohalide glasses were prepared. The absorption, emission properties, and local structure of the glasses were investigated. When excited at 808 nm diode laser, intense 1.32 and 1.55 μm near-infrared luminescence were observed with full width at half maximum （FWHM） of about 90 and 50 nm, respectively. The lifetime of the 1.32 μm emission varied due to changes in the local structure surrounding Dy^3＋ ions. The longest lifetime was over 2.5 ms, and the value was significantly higher than that in other Dy^3＋-doped glasses. Some other spectroscopic parameters were calculated by using Judd-Ofelt theory. Meanwhile, Ge-Ga-Se and GeSe2-Ga2Se3-CsI glasses showed good infrared transmittance. As a result, Dy^3＋-doped Ge-Ga-Se and GeSe2-Ga2Se3-CsI glasses were believed to be useful hosts for 1.3 μm optical fiber amplifier.

MoS_2 saturable absorber prepared by chemical vapor deposition method for nonlinear control in Q-switching fiber laser

Due to the remarkable carrier mobility and nonlinear characteristic, MoS2 is considered to be a powerful competitor as an effective optical modulated material in fiber lasers. In this paper, the MoS2 films are prepared by the chemical vapor deposition method to guarantee the high quality of the crystal lattice and uniform thickness. The transfer of the films to microfiber and the operation of gold plated films ensure there is no heat-resistant damage and anti-oxidation. The modulation depth of the prepared integrated microfiber-MoS2 saturable absorber is 11.07%. When the microfiber-MoS2 saturable absorber is used as a light modulator in the Q-switching fiber laser, the stable pulse train with a pulse duration of 888 ns at 1530.9 nm is obtained. The ultimate output power and pulse energy of output pulses are 18.8 mW and 88 nJ, respectively. The signal-to-noise ratio up to 60 dB indicates the good stability of the laser. This work demonstrates that the MoS2 saturable absorber prepared by the chemical vapor deposition method can serve as an effective nonlinear control device for the Q-switching fiber laser.

Linear and nonlinear optical properties of Sb-doped GeSe_2 thin films

Sb-doped GeSe2 chalcogenide thin films are prepared by the magnetron co-sputtering method. The linear optical properties of as-deposited films are derived by analyzing transmission spectra. The refractive index rises and the optical band gap decreases from 2.08 eV to 1.41 eV with increasing the Sb content. X-ray photoelectron spectra further confirm the formation of a covalent Sb--Se bond. The third-order nonlinear optical properties of thin films are investigated under femtosecond laser excitation at 800 nm. The results show that the third-order nonlinear optical properties are enhanced with increasing the concentration of Sb. The nonlinear refraction indices of these thin films are measured to be on the order of 10-18 m2/W with a positive sign and the nonlinear absorption coefficients are obtained to be on the order of 10-10 m/W. These excellent properties indicate that Sb-doped Ge-Se films have a good prospect in the applications of nonlinear optical devices.

Research progress of third-order optical nonlinearity of chalcogenide glasses

Chalcogenide glasses （ChGs） are a promising candidate for applications in nonlinear photonic devices. In this paper, we review the research progress of the third-order optical nonlinearity （TONL） of ChGs from the following three aspects： chemical composition, excitation condition, and post processing. The deficiencies in previous studies and further research of the TONL property of ChGs are also discussed.

The First-principles Study on the Optical Anisotropy of R3 Space Group Chalcogenides AX2MQ6

In order to explain the opposite phase matchability of two types of newly discovered chalcogenides, AX2MQ6 vs AX4M5Q12 belonging to the same R3 space group, the linear and nonlinear optical properties are calculated. The calculated Electron Localization Function（ELF） show the acentricity of the bonds on the Q^2- ions with sp^3 hybridization is the main origin of the optical anisotropy. To quantify such an acentricity, a geometric parameter, the dihedral angle between the tetrahedral undersides and the xy-planes is defined. And the calculated birefringence depends on the above defined geometric parameter and the ion radius. This correlation reasonably explains the opposite phase matchability of two closely related chalcogenide families of AX2MQ6 and AX4M5Q12 and is shedding useful light on further exploration on phase matchable IR-NLO crystals.

High efficiency of Brillouin scattering behavior in single-mode Ge–As–Se–Te fibers at 2μm

The Brillouin characteristics of step-index Ge–As–Se–Te(GAST)fibers at 2μm are designed and simulated on the basis of optical and acoustic properties.The refractive indexes of Ge_(20)As_(20)Se_(45)Te_(15)glass and Ge_(20)As_(20)Se_(43)Te_(17)glass serving as fiber core and cladding are 3.20 and 3.18 at 2μm,and their acoustic velocities are 2200 m/s and 2300 m/s,respectively.Numerical results indicate that the stimulated Brillouin scattering(SBS)efficiency is 248 m^(-1)·W^(-1),and the Brillouin threshold power is 66 m W when the core diameter of the 2-m-long GAST fiber is 4μm at 2-μm wavelength.The optic–acoustic coupling factor,the Brillouin frequency shift,and the Brillouin gain coefficient are 0.98,7.02 GHz,and 3.81×10^(-9)m/W,respectively.The SBS effect of GAST fibers simulated for the first time provides a new promising approach to selecting gain medium based on 2-μm-wavelength fiber laser.

Nonlinear optical properties of integrated GeSbS chalcogenide waveguides

In this paper, we report the experimental characterization of highly nonlinear GeSbS chalcogenide glass waveguides. We used a single-beam characterization protocol that accounts for the magnitude and sign of the real and imaginary parts of the third-order nonlinear susceptibility of integrated Ge23Sb7S70 （GeSbS） chalcogenide glass waveguides in the near-infrared wavdength range at λ = 1580 nm. We measured a waveguide nonlinear parameter of 7.0 4- 0.7 W-1 · m-1, which corresponds to a nonlinear refractive index of n2 =（0.93 ± 0.08） ×10-18 m2/W, comparable to that of silicon, but with an 80 times lower two-photon absorption coefficient βTPA = （0.010± 0.003） cm/GW, accompanied with linear propagation losses as low as 0.5 dB/cm. The outstanding linear and nonlinear properties of GeSbS, with a measured nonlinear figure of merit FOM TPA = 6.0 ± 1.4 at λ = 1580 nm, ultimately make it one of the most promising integrated platforms for the realization of nonlinear functionalities.

硫系光纤的非线性特性及其在全光开关上的应用

本文对目前红外光纤研究的热点 ,硫系光纤的非线性特性作了介绍 ,包括它的非线性系数n2 ,双光子吸收系数α2 ,响应时间 ,受激拉曼散射和群速度色散GVD的情况 。

基于半导体光放大器的双端口全光光开关

提出了一种基于半导体光放大器(SOA)的双端口全光光开关.这种开关以一个平行排列3×3耦合器作为其核心元件,具有类似于非线性光学环路镜(NOLM)和T比特光学非对称解复用器(TOAD)的结构.由于这种光开关是基于SOA的,所以它结构紧凑,易于集成,而且需要很小的控制光功率(几个mW).这种光开关具有两个开关端口,满足了一些特殊应用场合的需要.论文中给出了双端口全光开关的单脉冲2.5Gb/s开关实验结果.实验结果表明,这种开关可以实现两个端口的开关光信号同时输出,开关消光比达到了20dB以上.

小芯径硫系玻璃光纤的制备及其非线性光学应用

通过动态蒸馏提纯技术制备了高纯Ge-As-Se和Ge-As-S硫系玻璃。采用两步棒管法拉制了以Ge-As-Se玻璃为纤芯、Ge-As-S玻璃为包层的小芯径阶跃折射率光纤,并使用飞秒激光抽运光纤测试了超连续谱的产生。以Al和GaCl_3分别作为除氧剂和C/H纯化剂可以有效消除玻璃中的C、H和O杂质。制备的Ge As Se/Ge As S光纤在2~9μm波段表现出优异的传输性能,光纤数值孔径约为1.3;采用重复频率为10.5 MHz、脉冲宽度为320 fs、中心波长为4.0μm、峰值功率为4.6 k W激光抽运长度为22 cm、芯径为6μm的光纤,获得了覆盖1.9~8.2μm、光谱平坦度为±10 d B、平均功率为4.5 m W的超连续谱。

光子晶体光纤的非线性效应及其应用研究进展

光子晶体光纤在光器件的集成化、小型化乃至大幅降低其成本方面都有着重要的应用前景。介绍了光子晶体光纤的各类非线性效应及其潜在应用,重点讨论基于光子晶体光纤的光开关实现方案,并提出一种基于M Z干涉的光子晶体光纤光开关方案,对其可行性进行了探讨。

1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基类复合物在不同波长下的三阶非线性光学性质(英文)

合成了两种新的金属双噻吩类复合物:(苄基三乙基铵)双(1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基)-金(BTEAADT)和(苄基三乙基铵)双(1,3-二硫杂环戊烯-2-硫酮-4,5-二巯基)-镍(BTEANDT).采用Z扫描方法,在皮秒脉冲下,分别测试了两种材料的乙腈溶液在532和1064nm的三阶非线性光学特性.Z扫描的结果表明,BTEAADT的乙腈溶液在532nm具有反饱和吸收效应,在1064nm非线性吸收效应可以忽略且在两种波长都有自散焦效应,三阶非线性折射率为负值.BTEANDT的乙腈溶液在532nm非线性吸收效应可以忽略,在1064nm具有饱和吸收效应且在两种波长都有自聚焦效应,三阶非线性折射率为正值.分析了造成这种差异的原因.经过计算得到了两种材料在532和1064nm的三阶非线性折射率,三阶非线性吸收系数,三阶非线性极化率和超极化率.BETAADT的非线性折射率在532nm为-1.685×10-18m2·W-1,在1064nm为-1.459×10-18m2·W-1;BTEANDT的非线性折射率在532nm为1.452×10-18m2·W-1,在1064nm为7.311×10-18m2·W-1.两种材料的三阶非线性吸收系数,三阶非线性极化率和超极化率的数量级分别是10-11m·W-1,10-13esu和10-31esu.结果表明这两种材料在非线性光学领域有潜在的应用价值.

光纤传输特性及其在光网中的应用设计分析

对光纤的衰减、色散、非线性效应等传输特性作了阐述。结合应用要求，对光纤的种类及设计情况作了详细介绍和分析，并对光纤的选择应用作了分析说明。

利用光纤环形镜开关特性与孤子压缩效应获得无基座超短光脉冲

利用色散渐减光纤中高阶孤子非绝热压缩及非线性环形腔镜的消基座作用获得高质量无基座超短光脉冲。可以把波长为1.55μm,脉宽为20 ps的光脉冲压缩为1.42 ps无基座超短脉冲。并与直接用色散渐减光纤的非绝热孤子压缩得到的同宽度光脉冲分别在光纤正负色散区传输进行了比较,发现用色散渐减光纤构成的非线性光纤环形腔镜获得的压缩光脉冲具有相对理想的波形和频谱结构,有利于在光纤中长距离稳定传输。

中红外色散平坦渐减光纤设计

设计了一种以As2S3玻璃为纤芯、碲酸盐玻璃为微结构包层的锥形光子晶体光纤.该结构光纤兼具阶跃折射率光纤和光子晶体光纤双重特性,具有色散调制灵活性高且限制损耗低等优点.模拟结果表明：优化该光纤结构包层空气孔径、孔间距、纤芯直径等特征参量,使参量之间及参量与椎区长度之间满足特定线性关系时,该光纤在2~4.5μm中红外波段呈现色散平坦渐减特性;对该光纤微包层进行折射率~1.6的液体油填充处理,色散曲线对称性及平坦性得到进一步优化.该光纤在超短脉冲压缩与展宽、色散波、光孤子及中红外平坦超连续谱产生等领域应用潜力巨大.

五阶非线性对光纤中高斯型脉冲传输特性的影响

从含修正项的非线性薛定谔方程出发,采用变分法,导出了五阶非线性情况下光纤中高斯型脉冲参数随传输距离的演化方程组,求出了振幅与脉宽、频率与啁啾、脉宽与啁啾之间的三个解析约束关系,得出了脉宽随传输距离演化的解析解,讨论了五阶非线性对光纤中高斯型脉冲传输特性的影响。并且描绘了五阶非线性系数和啁啾对脉宽的影响、啁啾与初始啁啾对脉宽的影响、脉宽随传输距离以及五阶非线性系数、脉宽随传输距离以及初始啁啾四种情况下的三维图形。

硫系玻璃微结构缺陷对其二阶非线性光学性能的影响

采用传统的熔融淬冷法制备不同锗锑比的GeSbS硫系玻璃。通过研究玻璃的拉曼光谱、扫描电镜和电子探针显微分析后发现,硫系玻璃内部的微结构缺陷对其二阶非线性光学性能有显著影响,玻璃体系内存在的Sb2S3微晶或金属锑颗粒能使硫系玻璃在未经极化处理前就具有较大的二阶非线性光学性能;经电场温度场极化处理后,随着微晶的增多和进一步长大,导致GeSbS玻璃具有更高的非线性光学性能;由于Sb2S3微晶或金属锑的存在,导致玻璃具有较高的二阶非线性光学性能。