共查询到18条相似文献,搜索用时 203 毫秒
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单模光纤中啁啾脉冲的分裂机制 总被引:1,自引:1,他引:0
采用分步傅里叶算法数值求解非线性薛定谔方程,分析了单模光纤中不同情形下皮秒量级啁啾脉冲的分裂机制。结果表明,对于较短的脉冲(10 ps),啁啾脉冲分裂从高阶孤子压缩导致的脉冲塌陷开始;对于较长的脉冲(200 ps),脉冲分裂主要由调制不稳定性导致;对于介于两者之间的脉冲(50 ps),噪声使得脉冲分裂机制从高阶孤子压缩转向调制不稳定性。初始正、负啁啾能分别加速和延缓短脉冲分裂,而初始啁啾对长脉冲分裂影响很小。初始啁啾对脉冲分裂的影响与其分裂机制密切相关。 相似文献
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理论研究了氢分子离子在波长800nm短周期啁啾脉冲方案下的高次谐波发射与孤立阿秒脉冲产生。经计算发现,当选取合适的啁啾参数时可以限制高次谐波同时由两核发射,从而减弱其空间的相互干涉,得到光滑连续且只有单核贡献的高次谐波谱平台区域。当啁啾参数β=6、激光脉冲半峰全宽τ0=5fs时,通过在单核贡献的连续谱上截取100阶谱线宽度合成了持续时间约为98as的孤立阿秒脉冲。同时通过另一组参数计算也验证了当两核对高次谐波谱均有贡献时,不利于阿秒脉冲的产生。讨论中使用了经典的回碰动能图和时频分布图来解释高次谐波谱发射的物理机制。 相似文献
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三五阶非线性光纤中光脉冲的啁啾和频谱 总被引:2,自引:0,他引:2
为了探讨光纤的五阶非线性对光脉冲传输的影响,利用同时考虑三阶和五阶非线性效应的非线性薛定谔方程,在忽略光纤色散的情况下,解析并计算研究了超高斯光脉冲的非线性相移、频率啁啾。数值模拟了光脉冲传输的功率频谱。结果表明,与只有三阶非线性折射率的情形相比,正五阶非线性折射率的存在使光脉冲在光纤中传输的非线性相移和最大频率啁啾增大,使无啁啾光脉冲的频谱宽度变宽,谱峰数目增多,高斯脉冲初始啁啾对频谱的影响与三阶非线性折射率的情形类似;负五阶非线性折射率则使光脉冲传输的非线性相移和频率啁啾呈现新的特点,并使无啁啾光脉冲的频谱宽度变窄,谱峰数目减少。 相似文献
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基于光子晶体光纤(PCF)中脉冲演变遵循的非线性演化方程,用数值方法研究了反常色散情形下PCF中脉冲初始啁啾对超连续谱产生的影响,探讨了利用脉冲啁啾控制超连续谱产生的方法。结果表明:正、负啁啾均使谱展宽的速率变小,尤其是负啁啾情形,展宽速率更小,说明啁啾对谱展宽是不利的;在一定的初始条件下,光谱展宽存在一个最佳光纤长度,在这个长度处,光谱展宽最大,进一步增加光纤长度,谱宽基本保持不变;相对于变换极限脉冲来说,初始正、负啁啾脉冲对应的最佳光纤长度分别缩短和延长。 相似文献
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为了研究待测超短脉冲存在剩余啁啾对2次谐波自相关法测量脉宽产生的影响,以2次谐波自相关法测量原理为出发点,采用2次耦合波方程数值模拟计算了中心波长800nm、脉宽100fs的超短激光脉冲存在不同啁啾量时,经过偏硼酸钡(β-BaB2O4,BBO)晶体Ⅰ类非共线相位匹配进行2次谐波自相关测量对测量结果的影响。分析发现,正啁啾使测量值比实际值偏大,负啁啾使测量值偏小;负啁啾比正啁啾对脉宽测量的影响更大,当脉冲的啁啾参量C=20时测量误差为23%,而C=-20时测量误差高达53%;且测量误差随啁啾量的增大而增大。模拟计算了非线性晶体厚度对脉宽测量的影响,结果表明,选取较薄的非线性晶体能够有效控制啁啾量引起的测量误差,使用非线性晶体的厚度L≤0.5Ld可将脉宽测量误差控制在理想的范围。 相似文献
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Chao Wang Jianping Yao 《Photonics Technology Letters, IEEE》2008,20(11):882-884
A novel approach to generating linearly chirped microwave pulses in the optical domain based on spectral shaping and linear frequency-to-time mapping is proposed and experimentally demonstrated. In the proposed system, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is spectrum-shaped by an optical filter that consists of two superimposed chirped fiber Bragg gratings (SI-CFBGs) with different chirp rates. The SI-CFBGs form a Fabry-Perot cavity with a cavity length linearly dependent on the resonance wavelength, thus a spectral response with an increased or decreased free spectral range is generated. A chirped microwave pulse with the pulse shape identical to the shaped spectrum is obtained at the output of a high-speed photodetector thanks to the frequency-to-time mapping in a dispersive device. The proposed technique is experimentally demonstrated, a linearly chirped microwave pulse with a central frequency of 15 GHz and a chirp rate of 0.0217 GHz/ps is experimentally generated. 相似文献
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Hao Chi Jianping Yao 《Lightwave Technology, Journal of》2008,26(10):1282-1287
Chirped radio-frequency (RF) pulse generation based on optical spectral shaping and nonlinear wavelength-to-time mapping in a nonlinearly chirped fiber Bragg grating (NLCFBG) is investigated. In the proposed approach, the spectrum of a femtosecond pulse generated by a mode-locked fiber laser is shaped by an optical filter that has a sinusoidal frequency response. The spectrum-shaped optical pulse is sent to the NLCFBG, to implement nonlinear wavelength-to-time mapping. A chirped electrical pulse with the central frequency and chirp rate determined respectively by the first- and second-order dispersions of the NLCFBG is then obtained at the output of a high-speed photodetector. An approximate model that describes the chirped RF pulse generation is derived, which is verified by numerical simulations. Chirped pulse generation with a pulse compression ratio as high as 450 is demonstrated. The key device in the chirped RF pulse generation system is the NLCFBG, which is investigated in detail with an emphasis on the influence of its group delay ripples on the performance of the pulse generation system. Techniques to design and fabricate the NLCFBG are also discussed. The proposed approach provides a potential solution for the generation of chirped RF pulse with a high central frequency and large chirp rate for applications in pulse compression radar systems. 相似文献
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线性啁啾脉冲频谱干涉特性的模拟研究 总被引:1,自引:0,他引:1
为了研究宽带脉冲因受外界瞬态扰动而引起的相移随频谱变化的规律,利用啁啾脉冲与扰动在频域上的卷积特性,采取将频谱干涉技术和线性啁啾脉冲相结合,当两束线性啁啾脉冲在频率域相遇时,相同的频谱成分产生干涉,从其干涉图中得到随脉冲频谱变化的相对相移。根据傅里叶变换的频谱干涉技术,对从两束线性啁啾脉冲的频谱干涉图中提取相移进行了数值模拟。结果表明,对假设具有不同类型的相移进行重构,还原出随频谱变化的相位扰动。这一结果对超快光学中的瞬态测量是有帮助的。 相似文献
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《Lightwave Technology, Journal of》2009,27(16):3336-3341
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报道了一种新型的重复频率为10 GHz,脉宽为5.3 ps,抖动为184 fs的高稳定光短脉冲源.将大信号调制半导体激光器产生的10 GHz光脉冲,先送入LiNbO3电光相位调制器增强负啁啾,并使光谱进一步展宽,再通过色散补偿光纤(DCF)压缩脉冲啁啾,可得到光短脉冲.由于大信号调制激光器输出的光脉冲本身具有负啁啾,而通过相位调制器的光脉冲在不同的时间间隔内既有正啁啾也有负啁啾,通过适当调整进入相位调制器的光脉冲时延,使其通过相位调制器后累加产生更大的负啁啾,再利用正色散光纤压缩啁啾,从而得到低抖动且无基座的光短脉冲. 相似文献