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提出采用凸形色散平坦光纤(DFF-CVDP)传输亚皮秒啁啾孤子,利用分步傅里叶方法数值研究了亚皮秒啁啾孤子在DFF-CVDP中的传输特性,并与在线性色散平坦光纤(DFF-LDP)中的传输特性做了比较。结果表明,孤子脉冲在上述两种光纤中传输时,光纤损耗导致了孤子脉冲宽度随传输距离增加稍有展宽,脉冲方均根谱宽随传输距离增加逐渐减小。在DFF-LDP中,脉冲展宽更快,正啁啾对脉冲展宽的影响比负啁啾的影响更大,正啁啾对应的方均根光谱比其他情况下的宽得多。啁啾脉冲时域宽度随传输距离增加出现了衰减振荡,振荡周期和振幅随啁啾参量|C|的增加而增大。光孤子脉冲在两种光纤中传输时域波形保持不变,仍具有孤子特性。在DFF-LDP中,3β使得脉冲光谱红移从而诱导了脉冲时延,负啁啾减弱了3β的作用,正啁啾加强了β3的影响。在DFF-CVDP中传输可以忽略3β的影响。
Propagation of sub-picosecond chirp solitons using convex-shaped dispersion-flattened fibers (DFF-CVDP) is proposed. The propagation characteristics of sub-picosecond chirp solitons in DFF-CVDP are numerically investigated by using a step-by-step Fourier method. The transmission characteristics in flat optical fiber (DFF-LDP) are compared. The results show that when the soliton pulse propagates in the above two kinds of optical fibers, the optical fiber loss causes the pulse width of the soliton to broaden slightly with the increase of the transmission distance. The spectral width of the pulsed mean square decreases with the transmission distance increasing. In DFF-LDP, pulse broadening is faster, positive chirp has a greater effect on pulse broadening than negative chirp, and positive chirp corresponds to a much wider square root mean square spectrum than in other cases. The chirped pulse time-domain width appears attenuation oscillation with the increase of transmission distance, and the oscillation period and amplitude increase with the chirp parameter | C |. Optical soliton impulses transmit the time-domain waveforms in the two kinds of optical fibers, and they still have soliton characteristics. In DFF-LDP, 3β induced a pulsed delay induced by a red shift of the pulse spectrum, negatively chirped the effect of 3β, and positive chirp enhanced the effect of β3. The effect of 3β can be neglected by transmission in DFF-CVDP.