共查询到20条相似文献,搜索用时 31 毫秒
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利用激光脉冲在光纤光栅中传播时所遵守的相干耦合非线性薛定谔方程,研究了激光脉冲在局部高斯变迹布拉格光纤光栅中传输时,在反常色散区和正常色散区所产生的调制不稳定性。结果表明在反常色散区和正常色散区都能产生调制不稳定性;在反常色散区,当输入功率达到一定数值、传输距离一定时,当f=-1禁带之上能带底时,调制不稳定性增益的强度最强、宽度最窄;当远离能带底时强度减弱、宽度变宽;在正常色散区,在产生调制不稳定性功率区域,调制不稳定性存在并从给定值一直持续到无穷;并且,在反常色散区和在正常色散区,增益谱都受到局部高斯变迹函数的制约。 相似文献
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We exploit the large anomalous dispersion in the waist of a fiber taper to offset the intracavity normal chromatic dispersion of an Yb-doped fiber laser. The fiber taper provides sufficient anomalous dispersion to ensure soliton operation of the mode-locked laser. With the taper removed from the cavity, the laser operates in a net normal dispersion regime. 相似文献
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利用F-函数扩展法求解超介质中的超短脉冲传输方程, 探讨了超介质中的反常自陡效应和特有的二阶非线性色散效应所导致的新的孤子现象和规律. 结果表明, 正折射区的二阶非线性色散效应可以代替线性色散效应形成亮孤子; 正、负折射区的反常自陡效应由于其符号可改变, 从而可在特定条件下分别在反常色散和正常色散区形成有别于常规介质的亮、暗孤子; 反常自陡效应的符号或者反常自陡效应和三阶线性色散效应的相互比较关系能够控制亮、暗孤子中心的漂移方向.
关键词:
孤子
超介质
F-函数扩展法 相似文献
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从包含高阶色散的广义非线性薛定谔方程出发,得到了色散缓变光纤中交叉相位调制不稳定增益谱,研究了增益谱随入射功率及光纤纵向色散参量的变化关系.结果表明:由于四阶色散的影响,在色散缓变光纤的正、反常色散区,交叉相位调制不稳定均发生在两个频谱区.反常色散区两频谱区宽度均比正常色散区宽,且反常色散区第二频谱区更靠近零点,说明色散缓变光纤中交叉相位调制不稳定更容易发生在反常色散区.增益谱宽都随两入射光波功率比值的增加而增大.色散缓变光纤中交叉相位调制不稳定增益谱宽比常规光纤的宽,且随着光纤纵向色散参量μ的增大色散缓变光纤中交叉相位调制不稳定越来越明显. 相似文献
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具有高阶色散项的交叉相位调制不稳定性分析 总被引:15,自引:1,他引:14
以包含了三、四阶色散项的耦合非线性薛定谔方程为基础,重点研究了三、四阶色散对交叉相位调制不稳定性的影响。结果表明:三阶色散对调制不稳定性不起作用;当满足一定条件时,由于四阶色散的影响,不仅在光纤的反常色散区,而且在光纤的正常色散区,交叉相位所致的调制不稳定性均发生在两个频谱区。当光纤各参量及两束入射光波功率一定时,光纤反常色散区第一区域的增益谱要比正常色散区第一区域的增益谱宽;同时,反常色散区第二区域的增益谱比正常色散区第二区域的增益谱更靠近零点;进一步对比反、正常色散区的这两个频谱区,发现两个频谱区的范围有确定的对应关系。 相似文献
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We have investigated and compared the pulse evolutions in low and ultra-large anomalous dispersion erbium-doped fiber lasers
mode-locked by the nonlinear polarization rotation technique. Two lasers deliver the pulses that exhibit quite distinct characteristics
such as pulse duration, spectral width, and spectral sidebands. Experimental observations show that the spectral width decreases
from several nanometers to less than one nanometer whereas pulse duration extends about three times by changing the cavity
dispersion from −0.03 to −15.50 ps2. The solitons in ultra-large anomalous fiber laser show dips in the optical spectrum, which is quite distinct from that of
conventional solitons observed in low anomalous regime. 相似文献
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高阶色散导致的交叉相位调制不稳定性 总被引:2,自引:0,他引:2
在考虑光纤损耗及高阶色散的情况下,以三、四阶色散项的耦合非线性薛定谔方程为基础,研究高阶色散对交叉相位调制不稳定性的影响.研究表明:三阶色散对调制不稳定性不起作用;由于四阶色散的影响,在光纤的正常、反常色散区,交叉相位调制不稳定性均发生在两个频谱区.且反常色散区两频谱区都比正常色散区的宽,反常色散区第二频谱区比正常色散区的更靠近零点.光纤损耗对增益谱的谱宽有较大影响,它使增益的谱宽变窄,且随传输距离的增大谱宽变得更窄. 相似文献
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凹形色散分布光纤中超连续谱特性分析 总被引:5,自引:0,他引:5
比较了在不同色散分布的色散渐减光纤中超连续(SC)谱的产生。结果表明,当光纤的色散值关于中心波长对称、且随着传输距离增加,经由反常色散区过渡到正常色散区的、凹形色散分布的色散渐减光纤更有利于产生平坦、带宽的超连续谱。从频域的全场方程出发,模拟了脉冲在光纤中的传输情形,发现脉冲在凹形色散分布的光纤中传输时,不仅在反常色散区能更大程度被压缩,在正常色散区由于存在零色散波长点,还能更进一步展宽,从而得到更宽、更平坦的超连续谱。在谱强为-27dB时,谱宽可达到298nm,比相同情况下的凸形色散的光纤中超连续谱增宽97nm。结果显示,凹形色散分布的光纤比凸形色散分布的光纤在超连续谱的产生上有更明显的优势,可以得到更宽的超连续谱。 相似文献
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Yuandong Lei Guanghui Wang Weifeng Zhang 《Applied Physics A: Materials Science & Processing》2014,117(3):1437-1445
We investigate propagation behavior of electromagnetic waves in a slab uniaxial metamaterial waveguide with metal cladding and discuss the dispersion relation, group velocity and energy flux distribution of transverse electric guided modes in two kinds of uniaxial metamaterial waveguides with different orientations of optical axis in detail. The numerical results show that there exist anomalous dispersion properties such as backward modes existing in low-frequency range, and the group velocity can be negative or approach zero. If the orientation of optical axis is selected properly, each guided mode has two dispersion curves—one is normal dispersion and another belongs to anomalous dispersion and shows a transition from a backward mode to a forward one with the angular frequency increasing. In addition, the condition of the existence of cutoff frequency is clarified. These properties may have potential applications in optical information storage, optical communication, integrated optics and nanophotonic devices. 相似文献
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Tunable Supercontinuum Generated in a Yb~(3+)-Doped Microstructure Fiber Pumped by Ti:Sapphire Femtosecond Laser
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We experimentally demonstrate that a tunable supercontinuum(SC) can be generated in a Yb3+-doped microstructure fiber by the concept of wavelength conversion with a Ti:sapphire femtosecond(fs) laser as the pump.Experimental results show that an emission light around 1040 nm in an anomalous dispersion region is first generated and amplified by fs pulses in the normal dispersion region. Then, SC spectra from 1100 to 1380 nm and 630 to 840 nm can be achieved by combined effects of higher-order soliton fission and Raman soliton self-frequency shift in the anomalous dispersion region and self-phase modulation, dispersive wave, and four-wave mixing in the normal dispersion region. It is also demonstrated that the 20 nm change of pump results in a 280 nm broadband shift of soliton and the further red-shift of soliton is limited by OH-absorption at 1380 nm. 相似文献
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介绍了SC谱的产生机理,并通过数值计算具体分析和比较了各种光纤中高阶群速度色散(GVD)对SC谱产生的影响。结果表明:二阶GVD为正的光纤中,三阶GVD不利于平坦SC谱的形成;在色散位移光纤(DSF)的反常色散区,三阶GVD(TOD)是平坦SC谱形成的决定因素;四、五阶GVD则对反常色散平坦光纤(DFF)和色散平坦渐减光纤(DFDF)中平坦、宽带SC谱的形成起着决定性的作用。 相似文献
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采用矢量耦合非线性薛定谔方程描述了超短光脉冲在双折射光子晶体光纤中的传输过程,并利用分步傅里叶方法求解该方程。数值模拟了中心波长为1550nm的超短光脉冲在不同色散参量的双折射光子晶体光纤中超连续谱的产生及其偏振特性。分析了光纤在不同色散区时,高阶色散和非线性效应对超连续谱及其偏振态的影响。结果表明,当超短光脉冲波长位于近光纤零色散点的反常色散区时,比其在光纤正常色散区和远离光纤零色散点的反常色散区更容易产生宽且平坦的超连续谱,所得到的光谱显示出了复杂的偏振态特性。 相似文献
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Based on boundary conditions and dispersion relations, the anomalous propagation of waves incident from regular isotropic media into quasiisotropic media is investigated. It is found that the anomalous negative refraction, anomalous total reflection and oblique total transmission can occur in the interface associated with quasiisotropic media. The Brewster angles of E- and H-polarized waves in quasiisotropic media are also discussed. It is shown that the propagation properties of waves in quasiisotropic media are significantly different from those in isotropic and anisotropic media. 相似文献
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For optical fibers exhibiting a radially symmetric refractive index profile, there exists an analytical relation that connects waveguide dispersion and the Petermann-II mode field radius. We extend the usefulness of this relation to the nonradially symmetric case of microstructure fibers in the anomalous dispersion regime, yielding a simple relation between dispersion and effective mode field area. Assuming a Gaussian mode distribution, we derive a fundamental upper limit for the effective mode field area that is required to obtain a certain amount of anomalous waveguide dispersion. This relation is demonstrated to show excellent agreement for fiber designs suited for supercontinuum generation and soliton lasers in the near infrared. 相似文献
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采用预测校正分步傅里叶方法数值模拟了飞秒光脉冲在光子晶体光纤中的非线性传输和超连续谱产生,分析了初始光脉冲的中心波长、峰值功率和光纤长度在光子晶体光纤正、反常色散区对超连续谱形状和带宽的影响。结果表明,当初始光脉冲的中心波长在光纤的反常色散区时,产生的超连续谱宽要远宽于正常色散区,但是光谱的平坦性较差;当光脉冲中心波长在靠近零色散波长的反常色散区且其他脉冲参数不变的情况下,存在一个产生宽且平坦的超连续谱的最佳峰值功率和最佳光纤长度。对于超连续谱系统的优化设计与实际应用具有参考意义。 相似文献
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Weiqing Gao Zhongchao Duan Koji Asano Tonglei Cheng Dinghuan Deng Morio Matsumoto Takashi Misumi Takenobu Suzuki Yasutake Ohishi 《Applied physics. B, Lasers and optics》2014,116(4):847-853
We demonstrate the supercontinuum (SC) generation in a four-hole As2S5 chalcogenide microstructured optical fiber (MOF) experimentally. The As2S5 glass has better property of transmission than As2S3 glass in the visible range. The four-hole As2S5 MOF is fabricated by a rod-in-tube method. The SCs generated by different pump wavelengths at 2,000, 2,300 and 2,500 nm in the MOF whose length is from 2.3 to 20 cm are demonstrated. Those pump wavelengths correspond to the chromatic dispersion wavelength in the normal chromatic dispersion region, the anomalous chromatic dispersion region close to zero-dispersion wavelength (ZDW) and the anomalous chromatic dispersion region far from ZDW, respectively. Wider SCs can be obtained when pumped at a wavelength in the anomalous dispersion region close to ZDW. The widest SC range of 4,280 nm (from 1,370 to 5,650 nm) covering two octaves was obtained in a 4.8-cm-long fiber pumped at 2,300 nm. 相似文献