【作者】 闫晗；

【导师】 桑梅；

【作者基本信息】 天津大学 ， 光电子技术， 2007， 硕士

【摘要】 本文主要围绕非线性光学领域中的超短脉冲光源以及超连续谱的产生,结合实验室现有条件进行了如下工作:在被动锁模激光器部分,我们先对被动锁模光纤激光器的应用和分类进行了简单介绍,接着阐述了基于非线性偏振旋转(NPR: Nonlinear Polarization Rotation)效应的被动锁模光纤激光器的基本原理及光腔参数对输出脉冲特性的影响,并简要分析了频谱边带和多脉冲的产生机理,并构建起一套采用σ形腔的非线性偏振旋转被动锁模掺铒光纤激光器,实现了重复频率6.25MHz、脉宽691.2fs、中心波长1562.5nm、平均输出功率1.487mW的稳定自起振被动锁模脉冲输出。在超连续谱部分,我们分析了光纤中的自相位调制(SPM: Self Phase Modulation)、光纤群速度色散(GVD: Group Velocity Dispersion)、三阶色散(TOD: Third-Order Dispersion)、四波混频(FWM: Four Wave Mixing)和受激拉曼散射(SRS: Stimulated Raman Scattering)等非线性效应对超连续(SC: supercontinuum)谱特性的影响,并利用所构建的被动锁模光纤激光器经放大后泵浦不同色散特性和长度的光纤,完成产生超连续谱的实验。实验中,通过泵浦4.57km的色散位移光纤(DSF:Dispersion-Shifted Fiber)得到:小于泵浦波长一侧的15dB谱宽为330nm,大于泵浦波长一侧的20dB谱宽大于238nm的超连续谱。通过泵浦4.28km的色散平坦光纤(DFF:Dispersion-Flattened Fiber)得到:小于泵浦波长一侧的15dB谱宽为372nm,大于泵浦波长一侧的20dB谱宽大于232nm的超连续谱,并且在百纳米范围内的不平坦度<±0.25dB。更多还原

【Abstract】 This dissertation was focused on ultra-short pulse sources and fiber supercontinuum (FSC) pulse source, which include:In the section of passively mode-locked fiber laser, we introduced the applications and classification of the passively mode-locked fiber laser. Then, the physical mechanism of nonlinear polarization rotation (NPR) passively mode-locked fiber laser, spectral sidebands and multi-pulse generation were analyzed in theory. Aσ-shaped cavity nonlinear polarization rotation passively mode-locked erbium-doped fiber laser was built up. Stable, self-starting 691.2fs mode-locked pulse at 6.25MHz repetition rate was obtained with an average output power of 1.487mW and a center wavelength of 1562.5nm.In the section of supercontinuum, we studied the influences of the self-phase modulation (SPM), the group velocity dispersion (GVD),the third-order dispersion (TOD), the four-wave mixing (FWM ) and the stimulated Raman scattering (SRS) on supercontinuum(SC) spectrum. SC was generated in fibers with different dispersion characteristic and length. SC was generated from a 4.57km DSF with 691.2fs pump pulses, 330nm 15dB bandwidth spectrum shorter than pump wavelength was obtained, while on the opposite side more than 238nm 20dB bandwidth was also obtained. SC was generated from a 4.28km DFF with 691.2fs pump pulses, 372nm 15dB bandwidth spectrum shorter than pump wavelength was obtained, while on the opposite side more than 232nm 20dB bandwidth was also obtained with 0.25dB spectral uniformity over 100nm.更多还原