光纤非线性色散对类明孤子传输特性的影响

应用类明孤子在单模光纤中非线性传输特性的微扰理论，研究了光纤非线性色散对类明孤子传输特性的影响，导出了类明孤子参数演化的动力学方程。结果表明：光纤非线性色散微扰对类明孤子脉冲位置、频率和相位参数有影响，而对类明孤子脉冲振幅、脉宽、啁瞅参数无影响。     

光纤中三阶色散对类明孤子传输特性的影响

本文采用变分法，探讨了三阶色散存在时类明孤子在光纤中的传输特性，导出了类明孤子参数随传输距离的演化方程组，讨论了三阶色散对类明孤子传输特性的影响．     

光纤中非线性阻尼对类明孤子传输特性的影响

研究了光纤中非线性阻尼对类明孤子传输特性的影响,导出了类明孤子脉冲参数演化的动力学方程.对于常规单模光纤,光纤非线性阻尼将对类明孤子脉冲的振幅、脉宽、啁啾、频率和相位参数有影响,而对位置参数ξ无影响.     

类明孤子脉冲在单模光纤中传输特性的变分研究

应用变分法,研究了三阶色散对类明孤子脉冲在单模光纤中的传输特性,导出了类明孤子脉冲参数的演化方程组。     

存在Raman效应时NLS方程的变分求解

应用变分法．讨论了Raman效应对单模光纤中类明孤子传输特性的影响，导出了类明孤子参数演化的方程组，并得出了存在Raman效应时NLS方程的孤波解。     

三阶色散情况下光纤中类明孤子演化特性的研究

本文从含修正的非线性薛定谔方程出发，采用变分法，导出了三阶色散情况下光纤中类明孤子参数随传输距离的演化方程组；在此基础上，求出了振幅与脉宽、频率与啁啾及中心位置、脉宽与啁啾之间的三个约束关系和脉宽演化的解析解；讨论了三阶色散对类明孤子演化特性的影响。     

五阶非线性作用下光纤中类明孤子的演化特性

根据含五阶非线性微扰修正项的非线性薛定谔方程,采用变分法,导出了光纤中类明孤子各参数随传输距离演化的方程组,研究了脉宽与距离、啁啾与脉宽之间的关系,并对描述相位和频率的方程组用龙格-库塔算法进行了数值求解.结果表明:五阶非线性使类明孤子的脉宽压缩,可在一定程度上抵消初始啁啾和三阶色散对脉宽的展宽作用;五阶非线性对类明孤子的相位和频率演化特性的影响不明显,因而适度的五阶非线性(γ在0.0001到0.1之间)有利于类明孤子的稳定传输.     

三阶色散对光纤中啁啾类明孤子传输的影响

根据含三阶色散微扰修正项的非线性薛定谔方程,采用变分法,导出了三阶色散效应作用下光纤中具有初始啁啾的类明孤子各参数随距离演化的微分方程组,并用龙格-库塔算法对微分方程组进行了数值求解,数值结果表明:正三阶色散使脉宽展宽,负三阶色散使脉宽压缩,而初始啁啾总是使脉宽展宽,它们都导致相位与频率的抖动和更为严重的频率啁啾.为保证类明孤子稳定传输必须控制三阶色散系数和初始啁啾在很小(如≤0.0001)的范围内,采用三阶色散符号正负交替改变的光纤也有助于类明孤子稳定传输.     

光纤中五阶非线性对类明孤子传输特性的影响

本文采用变分法,考虑在五阶非线性情况下,修正的NLS方程的类明孤子的各参数随传输距离的变化特性。结果表明：五阶非线性情况下,类明孤子有很多不同于明孤子的特性。     

微腔半导体激光器泵浦的光孤子源研究

从微腔半导体激光器考虑相位变化的速率方程和光纤非线性薛定谔方程出发，数值模拟了交变电流注入下微腔半导体激光器内腔和光纤外腔中的光振荡过程，研究了光孤子形成的可能性。结果表明，合理选择自发发射因子、有源区体积、相位振幅耦合参数、附加相位参量等内外腔参数，可以实现稳定的孤子脉冲输出。     

Pedestal suppression from compressed femtosecond pulses using anonlinear fiber loop mirror

The compression of higher order soliton pulses in dispersion decreasing fibers (DDF's) generates ultrashort fundamental soliton-like pulses accompanied by a broad low-intensity pedestal component. In this paper, we investigate the subsequent removal of the pedestal using a nonlinear optical fiber loop mirror (NOLM) to produce high-quality pulses. The influence of higher order effects such as stimulated Raman scattering and third-order fiber dispersion on the pedestal removal from ultrashort pulses are considered, and the effectiveness of using dispersion-flattened fiber within the loop is shown. The technique is experimentally demonstrated for 540-fs pulses generated by compression in DDF. In this case, high-quality pulses are produced by pedestal removal using a NOLM constructed from dispersion-shifted fiber     

Demonstration of down-chirped and chirp-free pulses fromhigh-repetition-rate passively mode-locked lasers

Knowledge and control of the chirp parameters of semiconductor lasers is a prerequisite to obtaining transform-limited pulses and/or to compensate for group velocity dispersion in fiber. Here, we report measurements of the sign and magnitude of chirp in high-repetition-rate mode-locked semiconductor lasers. The chirp of these monolithic lasers is measured in the frequency domain, using filtering and cross-correlation techniques. For different injection currents, a range of different chirp values is measured, including strongly down-chirped pulses at higher injection currents and transform-limited pulses to slightly up-chirped pulses at lower injection currents. The pulse chirp and the resulting broadening are due to the algebraic addition of opposite-signed chirps due to saturation of the absorption section and the gain section. These may cancel each other under some conditions, leading to a soliton-like transform-limited pulse     

Polarization-maintaining fiber Bragg gratings for wavelengthselection in actively mode-locked Er-doped fiber lasers

Fiber Bragg gratings written in polarization-maintaining fiber are proposed for wavelength selection in actively mode-locked Er-doped fiber lasers. Combined with single-polarization optical circulator, they form unidirectional transmission filters that can be incorporated in polarization-maintaining laser cavities. We have fabricated such a grating in hydrogen-loaded PANDA fiber and we have incorporated it in a polarization-maintaining actively mode-locked Er-doped fiber laser designed to generate soliton-like pulses. Dependencies of pulse duration and spectral width on average intracavity power were measured. The power range over which soliton-like pulses were generated without pedestals was found to be ultimately limited by the grating's bandwidth     

Effect of tunable filter characteristics on the pulse performance of actively mode-locked fiber lasers

The effect of filter characteristics on the output performance of actively mode-locked fiber ring lasers has been studied experimentally and numerically, with the same 3-dB bandwidth, the filter that has a flatter wavelength response tends to generate narrower soliton-like pulses.     

Power scaling in passively mode-locked large-mode area fiber lasers

We report on a novel approach toward generating high peak powers in passively mode-locked fiber lasers. By appropriate design the fiber's mode area is increased by a factor of ~30 compared to standard fiber. This increased area effectively decreases the nonlinearity thus, increasing the power necessary to form stable soliton-like pulses     

光纤中随时间变化的三阶非线性对类明孤子传输特性的影响

从MNLS方程出发,考虑三阶非线性微扰的作用,采用变分法,求得拉格朗日密度函数表达式。在此基础上,推出了类明孤子脉冲参数随传输距离的演化方程组,讨论了三阶非线性微扰对类明孤子传输特性的影响。     

Dispersion effects in an actively mode-locked inhomogeheously broadened laser

We theoretically and experimentally studied the dispersion effects in an actively mode-locked inhomogeneously broadened laser. In the positive group velocity dispersion (GVD) region, the laser generates incoherent pulses. Self-phase modulation and resonant dispersion impede reduction of the pulse duration when the GVD is small or near zero. A single, stable, soliton-like pulse can be generated only when the GVD is within a certain range of negative values. When the negative GVD is too small, the laser generates only multiple soliton-like pulses because of excess gain filtering. When the negative GVD is too large, the soliton pulse-shaping process fails, and the laser generates only incoherent pulses due to insufficient gain filtering. In the experiment, we characterized an actively mode-locked inhomogeneously broadened Nd:silicate glass laser and confirmed this GVD dependence. The laser generated self-sustaining, soliton-like pulses as short as 77 fs.