线性光放大器的宽带自发辐射噪声分析

建立含有垂直光场(VCL)的线性光放大器(LOAs)稳态仿真模型,考虑了宽带噪声特性、端面反射和纵向空间烧孔效应。计算了在不同输入信号功率和垂直腔分布布喇格反射器(DBR)反射率下总的输出ASE噪声功率、噪声系数(NF)、前向和后向传输的ASE噪声光子速率和噪声谱分布的变化。结果表明,与传统光放大器(SOAs)相比,在增益非饱和区,LOA有很好的噪声钳制作用,ASE噪声几乎不随信号功率的改变而变化。在增益饱和区,破坏了VCL的钳制作用,NF有所上升,但上升的速率小于SOA。提高DBR反射率,总的输出ASE噪声功率减小,但NF有所增大。     

Amplified Spontaneous Emission in Slab Amplifiers

Amplified spontaneous emission (ASE) occurs in media with large gain, and affects both the magnitude and the spatial distribution of the inversion. In this work we theoretically study the effect of ASE in three-dimensional, rectangular slab amplifiers, using Monte Carlo type computer simulations. We found that in one-dimensional amplifiers ASE is always larger at the edges so that the inversion has a maxima at the center of the amplifier. However, in two- and three-dimensional amplifiers, the inversion has a minimum at the center of the amplifier for low gain, and a maximum at the center of the amplifier for high gain. Thus, the inversion profile can be changed by increasing the gain from a minimum at the center, through a plateau, to a maximum at the center. A simple analytical theory was developed and agrees with these results     

多段阵列式钕玻璃放大器中放大自发辐射问题的研究

由激光速率方程和泵浦速率的空间和时间分布出发，采用了二维光线追迹和蒙特卡罗法模拟了放大自发辐射，研究了多段阵列式钕玻璃放大器（ＭＳＡ）中间板条增益分布随时间和泵浦速率的变化。所得结果对大尺寸多段阵列式钕玻璃放大器的设计有参考价值     

Amplified Spontaneous Green Emission and Lasing Emission From Carbon Nanoparticles

In this work, the optical properties of carbon nanoparticles (CNPs) can be modulated by the dopant‐N atom and sp² C‐contents. CNPs prepared with the low urea mass ratio of 0.2:1 (CNP1) exhibit blue emission (maximum PL quantum yield: 15%). Increasing sp² C‐ and dopant‐N atom contents, as determined in CNPs prepared with high urea mass ratio of 2:1 (CNP2), lead to green emission (maximum PL quantum yield up to 36% in ethanol aqueous solution). Amplified spontaneous emission (ASE) can be observed only in CNP2 ethanol aqueous solution. Green lasing emission is achieved from CNP2 ethanol aqueous solution in a linear long Fabry‐Perot cavity, indicating the potential of CNP2 as a gain medium for lasing. CNP2 shows superior photostability compared with C545T dye. The green emission from CNP2 is speculated to arise from electron‐hole recombination (intrinsic state emission). The high PL quantum yield and small overlap between absorption and emissions of CNP2 ethanol aqueous solution are the key factors in realizing lasing emission.     

掺镱单模石英光纤中放大的自发辐射

描述了掺镱单模石英光纤中正向和反向放大的自发辐射 (ASE)的差异以及ASE谱轮廓随抽运功率、激活光纤长度和抽运波长等量的变化 ,这些结果对于掺镱光纤激光器、放大器的设计有重要的指导意义。     

太赫兹光非对称解复用器中自发辐射噪声特性分析

提出了一个在超短脉冲注入半导体光放大器 (SOA)时 ,在考虑了半导体带间效应以及带内效应 ,包括载流子热效应、谱烧孔效应、双光子吸收效应以及超快非线性折射效应的自发辐射噪声的计算模型。并利用该模型计算了放大自发辐射 (ASE)噪声对太赫兹光非对称解复用器 (TOAD)开关性能的影响。数值结果表明 ,在考虑ASE噪声情况下 ,TOAD的开关窗口的边沿更陡 ,在开关窗口的尾部还会出现明显的小峰。结果还表明 ,在输入为理想孤子脉冲下 ,即使考虑ASE噪声 ,在TOAD处于开的状态时 ,其输出信号的信噪比也大于 2 5dB。     

同步幅度调制控制孤子系统中自发辐射噪声的影响

运用微扰法分析了幅度调制控制孤子系统中自发辐射噪声对系统传输特性的影响，考虑了补偿增益变化对系统自发辐射噪声的影响，得到了比较准确的结果。发现补偿增益明显影响孤子到达时间的抖动。     

染料掺杂聚合物波导薄膜中的放大自发发射

利用简单的平板波导结构,在掺有机小分子激光染料ＤＣＭ的聚苯乙烯（ＰＳ）薄膜中,采用Ｎｄ：ＹＡＧ的三倍频激光束作泵浦源,在细条状增益区内,在脉冲激发能量为１２μＪ时,发生了增益窄化现象,在以５８０ｎｍ为中心处出现了光谱半高全宽（ＦＷＨＭ）只有２４ｎｍ的放大自发发射峰。     

钡蒸气中放大自发辐射与参量四波混频的竞争

研究了在双光子共振条件下，Ｂａ蒸气中放大自发辐射（ＡＳＥ）与参量四波混频（ＰＦＷＭ）的竞争过程，其机制可归结为ＡＳＥ与ＰＦＷＭ之间的干涉相消。     

高功率脉冲Er-Yb共掺光纤放大器中放大自发辐射的抑制方法

为了研究放大的自发辐射(ASE)对高功率脉冲Er-Yb共掺光纤放大器(EYDFA)的影响,采用数值模拟对EYDFA中不同参数信号的放大进行了研究。结果表明,Yb波段(1.0～1.1μm)ASE是制约放大器输出功率提升的主要因素。因此,有效地抑制Yb波段ASE将有助于放大器性能的提高。通过进一步研究发现,在放大器的抽运端引入一个Yb波段的辅助信号能有效地抑制Yb波段ASE,从而提高抽运转换效率,提升放大器的输出功率。     

Signal Design and Detection in Presence of Nonlinear Phase Noise

In optical fiber transmission systems using inline amplifiers, the interaction of a signal and amplifier noise through the Kerr effect leads to nonlinear phase noise that can impair the detection of phase-modulated signals. We present analytical expressions for the maximum-likelihood (ML) decision boundaries and symbol-error rate (SER) for phase-shift keying and differential phase-shift keying systems with coherent and differentially coherent detection, respectively. The ML decision boundaries are in the form thetas(r) = c₂r² + c₁r + c₀, where thetas and r are the phase and the amplitude of the received signal, respectively. Using the expressions for the SER, we show that the impact of phase error from carrier synchronization is small, particularly for transoceanic links. For modulation formats such as 16-quadrature amplitude modulation, we propose various transmitter and receiver phase rotation strategies such that the ML detection is well approximated by using straight-line decision boundaries. The problem of signal constellation design for optimal SER performance is also studied for a system with four signal points.     

Coupling of Organic Semiconductor Amplified Spontaneous Emission Into Polymeric Single-Mode Waveguides Patterned by Deep-UV Irradiation

Single-mode waveguides were fabricated by deep ultraviolet radiation in poly(methyl methacrylate) (PMMA). Using a masking process, the radiation modifies the refractive index of the PMMA forming core and cladding regions for waveguiding. Following the fabrication of the waveguides, the small molecule material aluminum tris(8-hydroxyquinoline) doped with the laser dye DCM is deposited directly onto the waveguide structures. By optical pumping (lambda=355 nm) amplified spontaneous emission was observed at the end facets of the waveguides     

放大自发辐射对全固态激光器调Q性能的影响

为定量分析放大自发辐射(ASE)对调Q激光器性能的影响,在调Q激光速率方程中引入放大自发辐射项,并在合理的近似下求解,给出了激光二极管(LD)端面抽运电光调Q运转的固体激光器反转粒子数的建立过程,分析了放大自发辐射对激光上能级储能效率的影响及考虑放大自发辐射时调Q激光器输出脉冲宽度和脉冲能量随抽运功率的变化关系。结果表明,由于放大自发辐射的存在,上能级储能效率降低,且在一定的抽运功率下,调Q输出脉冲宽度变宽,脉冲能量下降。用LGS(La3Ga5SiO14)晶体作电光调Q元件,在激光二极管抽运的Nd∶YVO4激光器上进行了实验,实验结果与理论分析结果基本吻合。     

四能级系统自发辐射场的非线性特性

研究在三个驱动场作用下四能级原子模型中量子干涉对自发辐射场的影响。通过求解相互作用表象下的运动方程得到系统自发辐射场共振模对应的原子电磁极化率随驱动场Rabi频率的变化规律。结果显示，此系统突破了传统非线性效应强场条件的限制，即使是弱的自发辐射场仍可具有强烈的非线性特性，这一新现象在量子器件制备，弱信号检测，量子信息处理等领域有重大应用前景。     

磷酸盐光波导激光器放大自发辐射的数值模拟

系统地研究了Er3 :Yb3 共掺磷酸盐玻璃波导的性质,在稳态情况下建立并求解速率方程.利用数值分析的方法模拟了980nm二极管激光器抽运时激光器的放大自发辐射(ASE)特性.模拟时用到的主要参数为:信号光的散射损耗α(1530)=8.2×10-2 dB/cm,980nm时Yb3 的吸收和发射截面积分别为5.4×10-25m2和6.9×10-25m2,980nm时Er3 的吸收和发射截面积分别为1.65×10-25m2和1.21×10-25m2,Yb3 Er3 间的能量传递系数为1.9×10-23m3/s,共谐上转换系数为8.09×10-25m3/s.     

宽带Er-Tm共掺石英光纤放大自发辐射特性分析

探索了新型Er-Tm共掺石英基质超荧光光纤光源的特性，在粒子数方程和功率传输方程的基础上对其放大自发辐射（ASE）特性进行了理论分析。在单向泵浦中，分析了泵浦功率和信号功率随光纤长度的变化特性，描述了在不同光纤长度、离子浓度及泵浦功率下信号谱的变化趋势；在双向泵浦中，讨论了泵浦功率和信号功率随光纤长度的变化特性以及信号谱相对于光纤长度和泵浦功率的稳定性。结果显示，利用Er-Tm共掺石英基质光纤可以获得稳定的100nm放大自发辐射带宽，大约是传统掺铒光纤超荧光光源带宽的两倍，但输出功率比后者低3个量级以上。     

Jitter and Amplitude Noise Accumulations in Cascaded All-Optical Regenerators

This paper proposes and demonstrates a simulation model to systematically investigate jitter accumulations in cascaded all-optical 2R regenerators. The simulation results indicate that when the pattern dependence from the memory effect is minimized, the jitter accumulation depends critically on the degree of the regenerative nonlinearity. Studies of tradeoffs between the jitter from bandwidth limitation and the signal-to-noise-ratio degradation help identify the optimized regenerator bandwidth for various degrees of regenerative nonlinearity. The simulation then considers the pattern dependence from the memory effect and finds that it can severely degrade the cascadability of an optical 2R regenerator and can make it worse than that of a linear optical amplifier (optical 1R). The simulation results show good matches to the experimental results of an optical 2R regenerator based on a semiconductor optical amplifier based Mach-Zehnder interferometer. To overcome the jitter accumulation associated with the optical 2R regeneration, we experimentally demonstrate an optical 3R regenerator for optical nonreturn-to-zero signals with all-optical clock recovery. The experiments achieve more than 1000-hop cascadability for pseudorandom binary sequence 2³¹-1 inputs with a 100-km recirculation loop using lab fiber. Field trial experiments then demonstrate a more than 1000-hop cascadability for a 3R spacing of 66 km and a 100-hop cascadability for a 3R spacing of 264 km.     

多级染料激光放大器中激光增益与放大自发辐射强度的理论研究

利用激光增益和放大自发辐射 (ASE)理论 ,对不同条件下的染料激光放大器的激光增益和ASE强度进行了数值计算。分析了当入射光强远小于和大于有效饱和光强时 ,激光增益和ASE强度与入射光相对强度的关系 ,讨论了在两种条件下ASE系数以及染料池端面反射系数对激光增益和ASE成分的影响。最后利用这些结果 ,对连续激光的多级染料放大系统的优化设计进行了讨论。     

Power Penalty From Amplified Spontaneous Emission in Spatial Diversity Links for Fade Mitigation

We investigate the power penalty caused by excess amplified spontaneous emission in an optically preamplified receiver for a communications link where a multiwavelength spatial diversity transmitter is used to mitigate atmospheric fading. We compare measured receiver sensitivity for a four-wavelength 10.7-Gb/s nonreturn-to-zero on–off-keyed system to theory using both the Gaussian noise approximation and chi square statistics.      

Bit-Error-Rate Evaluation of the Distributed Raman Amplified Transmission Systems in the Presence of Double Rayleigh Backscattering Noise

A new exact bit-error-rate evaluation method for distributed Raman amplification transmission systems in the presence of both amplified spontaneous emission and double Rayleigh backscattering (DRB) is developed based on a study of statistical characterization of DRB