光传输系统中SPM效应的研究

从理论上分析了单信道光传输系统中SPM效应对传输性能的影响,并通过仿真得出了不同入纤功率情况下SPM效应对单信道光传输系统影响的定量数据,当入纤功率小于0 dBm时,SPM效应不明显;入纤功率在0～12 dBm时,SPM效应减弱了色散效应的作用,延长了系统的受限距离;入纤功率大于15 dBm时,SPM效应起主导作用,单信道光传输系统极限受限功率为18 dBm.     

10 Gbps optical soliton transmission link using in-line SOA on standard SMF at 1.3 μm

In this paper, 10 Gbps optical soliton transmission link using in-line semiconductor optical amplifiers (SOAs) for already installed standard single mode fibers (SMF) at 1.3 μm wavelength has been reported. The pattern effect and the impact of chirp on pulse propagation after amplification have been investigated. The observations are based on modeling and simulation optical soliton transmission link. Optical soliton pulse transmission over distances of the order of several hundreds of kilometers has been shown with and without initial chirp.     

Investigation of optimum pulse shape for 112 Gbps DP-DQPSK in DWDM transmission

This paper reports the simulative analyses to investigate the impact of different pulse shapes on DP-DQPSK modulation for high-spectral efficient DWDM transmission at 112 Gbps per channel. In the simulation model we have considered three different pulse shapes viz. NRZ, 50% duty cycle RZ (RZ50) and 67% duty cycle RZ (RZ67) in symbol-aligned and symbol-interleaved format. The analysis has been carried out for various linear and nonlinear system impairments where the pulse is subjected to degradation under the influence of amplified spontaneous emission (ASE) noise, group velocity dispersion (GVD), cross-phase modulation (XPM) and polarization mode dispersion (PMD) and thus, limiting the system performance. Results show that the RZ50 pulse shape for DP-DQPSK with symbol interleaving shows the maximum tolerance for the various system degradations in long haul DWDM transmission. Even the system based on the NRZ pulse shape can gain significant improvement from the symbol-interleaving.     

Soliton Propagation in Birefringent Fibers

In this article, the propagation of solitons in a single mode fiber with polarization mode dispersion (PMD) is analyzed. In optical fibers, the randomly varying birefringence degrades soliton transmission system in two aspects. First, the dispersive waves cause pulse broadening. Second, the dispersive waves interact with other soliton pulses. Here we studied the effects of PMD on a single pulse and the variation of pulse broadening, energy decay, and degree of polarization on a single soliton pulse propagating over a very long distance.     

Effect of group velocity dispersion on femtosecond pulse evolution in quantum well waveguide structures

The paper deals with the theoretical investigation of ultrafast-pulse evolution in a semiconductor quantum well (QW). Semiconductor Bloch equations are used to obtain the polarization induced in the medium due to incident Gaussian electromagnetic beam. The partial differential equation with finite group velocity dispersion (GVD) is then used to analyze the effect of induced polarization on the pulse. The role of GVD on femtosecond pulse evolution in GaAs/AlGaAs waveguide is studied, giving due consideration to the intensity dependent group velocity of the medium.     

超短光脉冲在光纤中传输计算机模拟计算的研究

本文提出了一种研究超短光脉冲在介质中传输特性的简单的计算机计算方法.用该方法得到了正色散光纤中的频率调制、频谱加宽和方波自成形,以及负色散光纤中的一、二、三阶孤子传输.其数值计算结果与解非线性薛定谔方程的数值结果完全一致.     

用光束脉冲矩阵研究多色光学谐振腔

用光束脉冲矩阵法分析了多色光学谐振腔的稳定条件；给出了计算腔内净群速度色散的准确表达式。具体分析了一种新型自锁模谐振腔，计算了它的腔内净群速度色散数值，为研究它的锁模机理提供了可靠的数据。     

Analytic solutions of self-similar pulse based on Ginzburg-Landau equation with constant coefficients

Based on the constant coefficients of Ginzburg-Landau equation that considers the influence of the doped fiber retarded time on the evolution of self-similar pulse, the parabolic asymptotic self-similar solutions were obtained by the symmetry reduction algorithm. The parabolic asymptotic amplitude function, phase function, strict linear chirp function and the effective temporal pulse width of self-similar pulse are given in this paper. And these theoretical results are consistent with the numerical simulations. Supported by the Natural Science Foundation of Guangdong Province of China (Grant No. 04010397)     

Research on the nonlinear pulse propagation by numerical analysis

Based on the computation approaches of numerical analysis in electromagnetic, the nonlinear pulse propagation in optical fiber is investigated in this paper. The transforming rule of the shape and spectrum of Gauss pulse are also researched in chirped and non-chirped scenarios from the nonlinear Schrödinger equation (NLSE). Analyzing the transient wave behavior in time domain and frequency domain respectively, the compression effect of chirp is also presented at different propagation distance. Then by the nonlinear Schrödinger equation, we discuss a specific solution in the quasi soliton without distortion, which has the stable propagation properly, and do the numerical simulation in soliton wave. Finally, by selecting proper fiber structure parameters and adjusting the width in soliton pulse, the soliton communication system can be optimized.     

Slow light in photonic crystal with combinations of gradient dielectric constant

A line defect waveguide formed by a new kind of two-dimensional photonic crystal with combinations of gradient varied dielectric was designed and the properties of slow light will been studied by using the Plane Wave expansion Method (PWM). The result shows that the group velocity is slower when the corresponding combination of gradient dielectric constants are with higher dielectric constant and lower interval. In our new structure of photonic crystal, the corresponding group velocity can reach as low as 0.06c (c: light velocity in vacuum), two orders magnitude lower than light velocity. Meanwhile, the group velocity dispersion effect is relatively small.