Effects of gordon-haus jitter on soliton transmission

The bit error rate (BER) performance of an optical soliton communication system is analyzed. Based on the jitter variance equation and the chi-square distribution for the amplified spontaneous emission noise, an analytic expression for the BER calculation is obtained. We have investigated the effects of Gordon-Haus jitter, which is due to the random phase shift of the soliton individual central wavelength induced by the amplified spontaneous emission noise of the amplifiers. Very good agreement has been obtained between our theory and the reported experimental results.     

Analysis of bit error rate in an optical soliton communication system

An analytical model to describe the Gordon-Haus jitter has been introduced. We have analysed the effects of accumulated amplified spontaneous emission and Gordon-Haus jitter on the bit error rate (BER) performance for various digital modulation formats (that is, ASK, FSK and DPSK).     

Effect of Four-Wave Mixing on Optimal Placement of Optical Amplifier in WDM Star Networks

In this article, the effect of four-wave mixing (FWM) and amplified spontaneous emission (ASE) noise on WDM optical star networks has been investigated. Analysis for the evaluation of probability of error has been carried out (a) when only FWM is present and (b) when both FWM and ASE noise are present. Numerical results are presented in the graphical and tabular forms for the practical values of parameters. Finally, optimal location of the amplifier in the network has been identified as being before the star coupler preceding the receiver.     

Effect of Four-Wave Mixing on Optimal Placement of Optical Amplifier in WDM Star Networks

In this article, the effect of four-wave mixing (FWM) and amplified spontaneous emission (ASE) noise on WDM optical star networks has been investigated. Analysis for the evaluation of probability of error has been carried out (a) when only FWM is present and (b) when both FWM and ASE noise are present. Numerical results are presented in the graphical and tabular forms for the practical values of parameters. Finally, optimal location of the amplifier in the network has been identified as being before the star coupler preceding the receiver.     

L波段掺铒光纤放大器的自发辐射谱与增益的研究

利用Giles模型对L波段掺铒光纤放大器小信号增益特性进行了数值模拟,模拟结果表明最佳铒纤长度并不是一定值,它随输入信号波长的不同而改变,较短的波长对应较短的光纤长度;在数值模拟、分析的基础上,分别采用7m和9m的L波段铒光纤构成长波段掺铒光纤放大器,通过实验测量,分析比较了它们的自发辐射谱以及增益和噪声指数,得到了光纤长度对L波段增益谱、噪声指数和自发辐射谱的影响规律;最后,辅以C波段掺铒光纤放大器加以分析,指出了适合于放大L波段信号的最佳自发辐射谱型。     

Numerical and experimental investigation on ASE effects in high-power slab amplifiers

A three-dimensional calculation of the amplified spontaneous emission (ASE) is presented that allows rapid determination (with suitable approximation techniques) of the gain-length product (GLP) in high-power slab amplifiers. These calculations include non-saturable absorption, ASE line-narrowing effects, and total internal reflections (TIR) at the pumping surfaces. A parametric study of the slab geometry is presented and compared with experimental results. A good qualitative agreement between theory and experiment is achieved.     

Analysis of a DPSK soliton transmission system

We present a closed form expression to analyse the error performance of a differential phase-shift keying (DPSK) digital modulation format in an optical soliton communication system. In the analysis we include the effect of Gordon-Haus jitter, which is mainly due to the amplified spontaneous emission noise of the amplifiers. Gordon-Haus jitter is found to be less significant when the bit period is 15 times greater than the jitter variance and becomes more significant when the signal-to-noise ratio is greater than 20 dB. Due to a good bit error rate (BER) performance (BER ≈ 10⁻²⁰at SNR= 21 dB), the DPSK modulation format has a potential application for a high-bit-rate and low-noise soliton communication system.     

Effect of different metal-backed waveguides on amplified spontaneous emission

We investigate the effect of a metallic electrode on the ability for poly[2-methoxy-5-(2’-ethylhexyloxy)-1,4phenylene vinylene](MEH-PPV) film to undergo amplified spontaneous emission(ASE).The threshold of the device with Ag cladding is about 10 times greater than that of a metal-free device,but metal such as Al completely shuts off ASE.The ASE recurs when a thin spacer layer,such as a few nanometers of SiO 2,is introduced between the MEH-PPV film and the Al cladding.Compared with the Cu or Al electrode,the Ag cladding is most suited to serve as an electrode with its low optical loss due to its high work-function and reflectivity.     

有机材料EnBOD的放大自发发射性能研究

在紫外脉冲激光泵浦条件下,研究了有机材料EnBOD的放大自发发射(ASE)性能.EnBOD的甲苯稀溶液样品具有较窄的吸收和荧光光谱,主峰分别位于508 nm和527 nm.其ASE效率随着溶液浓度而变化,浓度为0.008 mol·L-的EnBOD样品具有最高的ASE效率,达到22.6％.其ASE主峰位于542 nm,阈值约为29.5 kW·cm-2.阈值后的ASE半宽约为12.4 nm.经紫外脉冲激光20万次泵浦后,ASE的光强衰减为初始强度的61.2％.结果表明EnBOD是一种ASE阈值较低、光稳定性良好的激光材料.     

交叉增益调制型波长转换器噪声特性的研究

对基于半导体光放大器的交叉增益调制型波长转换器相向和同向两种工作方式进行了研究。实验上分别实现了两种工作方式在1550nm波段的波长转换,比较了相同外部条件下两种工作方式的噪声特性,在全面考虑放大自发辐射噪声及其消耗载流子,增益谱的色散性和有源区内部损耗等因素的基础上,运用放大器的分段模型,计算了不同条件下两种方式的输出噪声功率,结果表明：相向型工作方式受放大自发辐射噪声的影响要远大于同向工作方式,输出放大自发辐射噪声功率的大小主要取决于载流子浓度的高低,而载流子空间分布的不均匀程度则决定两种工作方式输出噪声功率的差值大小。     

放大自发辐射对激光冲击处理7050铝合金的影响

利用高功率钕玻璃激光器对7050铝合金表面进行了冲击处理,保持泵浦功率不变,用压电传感器和示波器测试了激光冲击产生的压力波形,用X射线应力测量仪测量了激光冲击后铝合金表面的残余应力,并用非接触式光学轮廓仪分析了激光冲击后铝合金的表面形貌,研究了放大自发辐射强度对激光冲击处理7050铝合金冲击压力、残余应力和粗糙度影响的微观机理。研究结果表明:在泵浦功率不变前提下,放大自发辐射强度的增大降低了激光冲击波压力,铝合金表面残余压应力也随之降低,同时铝合金表面粗糙度增大。     

1137 nm长波掺镱光纤激光器的出光实验

分别使用976 nm半导体激光器和1040 nm光纤激光器作为泵浦源,实现了1137 nm长波光纤激光器的出光,输出功率均超过百mW。激光器采用相同的线性腔结构,高反光栅和低反光栅的反射率分别为99.6%和39.7%,增益介质是一段8 m长的掺镱光纤,纤芯直径5 m。当976 nm半导体泵浦功率为912 mW时,1137 nm激光输出功率为182 mW,对应的斜率效率为28.5%;当1040 nm激光功率为1.59 W时,输出的1137 nm激光功率为278 mW,斜率效率约为25%。在此基础上对两种泵浦方式进行了对比分析。     

准分子激光放大器中的三维放大自发辐射效应

发展了小纵横比条件下、具有圆柱对称性介质的高功能ＫｒＦ准分子激光放大器中，放大自发辐射效应的三维理论模型和计算程序。考虑自发辐射的频率分布效应以及侧壁表面反射效应。结果分析表明，当纵横比及入射负载均较小时，放大自发辐射对输出光束质量有较大的影响。     

超短脉冲染料放大器中的参数研究

对超短脉冲染料放大器(DLA)中放大的自发辐射(ASE)随泵浦强度变化的关系进行了实验研究,为了求得具有高储能、低自发辐射背景噪声的染料激光放大器的泵浦强度,我们用速率方程对实验结果进行了解析分析,获得了染料激光放大器的泵浦强度与染料参数(浓度、增益长度等)的近似关系式,以及相应条件下染料激光放大器储能和小信号增益的表达式,并与实验进行了比较.二者符合较好,从而为染料激光放大器的设计提供了参考.     

Solvent-vapour treatment induced performance enhancement of amplified spontaneous emission based on poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene]

In this work,performance enhancements of amplified spontaneous emission(ASE) from poly[2-methoxy-5-(2éthyl-hexyloxy)-1,4-phenylene vinylene](MEH-PPV) have been achieved via solvent vapour treatment.Correlations between the morphology of the film and the optical performance of polymer-based ASE are investigated.The active layers are characterised by atomic force microscopy and optical absorption.The results show that the solvent-vapour treatment can induce the MEH-PPV self-organisation into an ordered structure with a smooth surface,leading to enhanced optical gain.Thus the solvent-vapour treatment is a good method for improving the optical properties of the MEH-PPV.     

基于环行腔激光器四波混频型可调谐波长转换的理论研究

建立了完整的基于半导体环行腔激光器四波混频型可调谐波长转换器的宽带理论模型.模型中考虑了半导体光放大器的材料增益谱、载流子的空间分布、光场的纵向空间分布和宽带放大自发发射等关键因素，并通过数值模拟，从理论上研究了这种波长转换器的各种性能与输入信号光功率、注入电流、输出耦合器的耦合比和环行腔激光器激射光波长的关系.理论上所得结论与文献中实验结果符合得很好. 关键词： 半导体环行腔激光器 四波混频 波长转换 放大自发发射     

WDM系统中ASE噪声的二阶色散效应

讨论了采用小信号分析法研究脉冲波在色散、非线性光纤中的传输时,放大的自发辐射(ASE)噪声作为功率调制项加入脉冲波的传输方程后所产生的效应.ASE噪声不仅被互相位调制不稳定增益所放大,还受二阶色散成分的影响.其传输函数为COS(1/2β2dzω2),这一函数不能通过色散补偿来消除,会削弱ASE噪声的影响.鉴于此,ASE...     

放大自发辐射对激光冲击处理7050铝合金的影响

 利用高功率钕玻璃激光器对7050铝合金表面进行了冲击处理,保持泵浦功率不变,用压电传感器和示波器测试了激光冲击产生的压力波形,用X射线应力测量仪测量了激光冲击后铝合金表面的残余应力,并用非接触式光学轮廓仪分析了激光冲击后铝合金的表面形貌,研究了放大自发辐射强度对激光冲击处理7050铝合金冲击压力、残余应力和粗糙度影响的微观机理。研究结果表明:在泵浦功率不变前提下,放大自发辐射强度的增大降低了激光冲击波压力,铝合金表面残余压应力也随之降低,同时铝合金表面粗糙度增大。     

Effects of temperature on the stability of separatescreening bright--dark spatial soliton pair

We investigate theoretically the temperature effects on the evolution and stability of a separate screening bright--dark soliton pair formed in a serial non-photovoltaic photorefractive crystal circuit. Our numerical results show that, for a stable bright--dark soliton pair originally formed in a crystal circuit at given temperatures, when one crystal temperature changes, the soliton supported by the other crystal will evolve into another stable soliton if the temperature change is quite small, whereas it will become unstable and experience larger cycles of compression or break up into beam filaments if the temperature difference is big enough. The dark soliton is more sensitive to the temperature change than the bright one.     

MEH-PPV薄膜的放大自发发射特性

研究了MEH-PPV薄膜的放大自发发射特性。当激发强度增加时,从样品边缘发射的光谱发生增益窄化现象并具有明显的阈值特性。我们发现随着薄膜厚度的增加,MEH-PPV薄膜的阈值有所降低,而其增益系数则随之增加。在150nm厚时测得最大净增益系数为25.03cm^-1,最低阈值为2.2μJ/pulse。结果表明MEH-PPV是一种优良的激光和光放大材料。