【作者】 董永康；

【导师】 吕志伟；

【作者基本信息】 哈尔滨工业大学 ， 物理电子学， 2008， 博士

【摘要】 自从2004年D. J. Gauthier提出光纤中基于受激布里渊散射(Stimulated Brillouin scattering, SBS)的慢光和快光思想以来,SBS慢光就一直是慢光领域的研究热点。但是由于SBS固有的特性,使得SBS慢光存在有限的慢光延时和较窄的慢光带宽这两个限制。针对这两个问题,本论文提出了一些创新的解决方案,并进行了理论和实验研究。首先,从SBS耦合波方程出发,对光纤中基于SBS的慢光和快光进行了理论研究。分别研究了SBS慢光的稳态小信号解析解、稳态数值解和瞬态数值解。对于稳态小信号情形,SBS慢光延时有解析表达式,它与布里渊增益成正比,与布里渊增益带宽成反比;然而进入增益饱和区后,由于泵浦抽空效应,使得延时开始减小甚至出现负值。对于Stokes脉宽小于声子寿命的瞬态情形,由于声波场迟滞产生的新脉冲引入了一个附加延时,并且会导致脉冲的严重展宽和畸变。其次,为了拓展有限的SBS慢光延时,提出了使用布里渊光纤环形放大器进行多次布里渊放大,从而增加可调延时的思想,并在实验上进行了验证。实验上我们获得了脉宽为40ns的探测脉冲在布里渊光纤环形放大器中得到八圈的布里渊放大,共获得215ns的可调延时,相对延时为5.4。最后,为了提高SBS慢光带宽,提出多增益谱叠加来获得宽带布里渊增益谱的方法,并且提出了采用多频调相技术获得多条等幅光谱线的方法。首先我们在理论和实验上分别获得了三条、五条、七条、九条和十一条等幅光谱线的光谱;然后,利用获得的具有多条等幅光谱线的泵浦光进行了宽带SBS慢光实验,利用基频为30MHz的十一等幅光谱线,获得了最高为570MHz的布里渊增益带宽。而且,实验结果表明更宽更平的布里渊增益谱可以在一定的展宽因子内获得更大的相对延时。更多还原

【Abstract】 SBS slow light has been at the research focus in slow light optics community since the fast and slow light based on Stimulated Brillouin scattering (SBS) was proposed by D. J. Gauthier in 2004. Due to the inherent characteristics of SBS, there are still two problems in SBS slow light: the limited slow light delay time and the narrow Brillouin gain linewidth. To address the two problems, this dissertation proposes some innovative solutions, and performs theoretical and experimental studies.First, we theoretically study the SBS fast and slow light in an optical fiber based on the SBS coupled wave equations. We study the analytic solutions in stable state with small-signal and the numerical solutions in stable state and transient state, respectively. In the case of stable state with small-signal, SBS slow light delay time can be expressed by an analytic expression, which is proportional to the Brillouin gain parameter and inversely proportional to the Brillouin gain linewidth; while in region of gain saturation, due to the effect of pump depletion, the delay time becomes decreasing and even negative. In the case of transient state when probe pulse duration is smaller than phonon lifetime, a new pulsle induced by the delayed acoustic wave adds an additional delay time and induces large pulse distortion and broadening.Second, to extend the controllable delay time, we propose a method based on a Brillouin optical fiber ring amplifier where the probe pulse can be amplified with multiple times in it. In experiment, a maximum time delay of 215 ns, larger than five times of the input probe pulse duration of 40 ns, has been obtained after experiencing eight loops of Brillouin amplification.Finally, to broaden SBS linewidth, we propose a method to obtain broadband Brillouin gain linewidth by overlapping multiple gain spectrums, and a method to obtain multiple equal-amplitude spectral lines using the technique of multi-frequency phase modulation. First, we have theoretically and experimentally obtained three, five, seven, nine and eleven equal-amplitude spectral lines, respectively; then we have performed the broadband SBS slow light experiment using pump with multiple equal-amplitude spectral lines, obtaining a maximum Brillouin linewidth of 900 MHz using eleven equal-amplitude spectral lines with the fundamental frequency of 30 MHz. The experimental results also indicate that broader flattened Brillouin gain spectrum can produce larger fractional delay at a fixed broadening factor.更多还原