全光3R再生系统中的全光时钟提取技术研究

发布时间：2018-03-17 04:35

本文选题：全光3R再生技术　切入点：法布里-珀罗腔　出处：《江南大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着信息技术的发展,光纤通信的传输速率越来越快,当速率超过40Gbit/s时,由于电子瓶颈的存在,必须使用全光器件对恶化的光信号进行全光3R再生,这就使得全光3R再生中的时钟提取技术变得十分重要。本文中对利用F-P腔进行全光时钟提取方案展开研究。针对光纤光栅进行优化。利用光纤光栅优化恢复出的时钟的效果,得到效果较好的单波长时钟信号。首先利用F-P腔的结构分析了光在腔内的传输方式,推导出F-P腔的传输方程,给出了F-P腔的重要参数自由光谱区fFSR以及精细度F。在反射率R不同的时候对F-P腔的功率谱进行了仿真,得出了R越大,透射窗口越窄的结论,并研究了精细度F和R之间的关系,得出了大约在R=0.95时,精细度有一个飞速的提升,之后通过耦合模理论研究并分析了光纤光栅的基本原理,直接求解均匀光栅以及通过传输矩阵法啁啾光栅的耦合模方程,并使用Matlab仿真出各种光栅的反射谱。其次通过参变量值的改变来研究光栅的特性。着重研究了长度、折射率调制深度、均匀光栅的有效折射率;啁啾光栅的啁啾系数分别对反射率峰值、带宽、时延抖动的影响。对光纤光栅F-P腔进行仿真,研究了在两个光栅完全相同时光栅长度,折射率调制深度,腔长以及有效折射率的改变对反射谱的影响;两个光栅的光栅长度以及折射率调制深度分别不同时对反射谱的影响。之后,针对啁啾光栅反射谱顶端存在着抖动的情况,首先使用常用切趾技术进行优化,发现了其切趾后带宽变小,倾斜度增加,随后使用对称切趾对上述情况进行改进,发现对称切趾对于带宽和倾斜度有一定的补偿,但是顶端仍然存在抖动,引申出采取非对称切趾技术做进一步的改进,将光栅分成三段并通过研究高斯控制参数a和切趾前后半高全宽的变化以及切趾前后平均时延波动的变化得到每一段的最佳高斯控制参数分别为a1=8,a2=4,a3=5最终利用其作出啁啾光栅的仿真。最后,利用普通F-P腔进行40GHz的光时钟信号的提取,并比较平面镜的反射率R分别是0.9、0.93、0.99、0.999时恢复出的时钟信号的频域图和时域图,得出精细度越大恢复出的时钟效果越好的结论。但精细度过大时,透射窗口很窄,将会导致难以对准,且优化效果并不明显,所以选用R=0.99继续后续研究。由于单波长的时钟信号只要约0.96nm的带宽,首先尝试使用光纤光栅F-P腔进行单波长时钟信号的提取,但是其透射窗口的不可控故此种方案的不可行。随后改用光栅先对光信号进行滤波,但是光栅反射谱都不是理想的带通滤波器,所以进入F-P腔的信号存在抖动,时钟提取效果不理想,并指出实际应用中均匀光栅在切趾后,带宽很难达到0.96nm。最终利用第四章的切趾技术消除啁啾光栅的反射谱顶端的不平坦后,结合第三章的啁啾光栅特性通过增加折射率调制深度到Δneff=1*10-4增大其反射率峰值,以获得更好的恢复效果。
[Abstract]:With the development of information technology, the transmission rate of optical fiber communication is getting faster and faster. When the rate exceeds 40Gbit / s, due to the existence of electronic bottleneck, it is necessary to use all-optical devices to regenerate the deteriorating optical signal. This makes the clock extraction technique of all-optical 3R regeneration very important. In this paper, the scheme of all-optical clock extraction using F-P cavity is studied. A good single wavelength clock signal is obtained. Firstly, the optical transmission mode in the cavity is analyzed by using the structure of the F-P cavity, and the transmission equation of the F-P cavity is derived. The important parameters of F-P cavity, fFSR and fineness F, are given. The power spectrum of F-P cavity is simulated when the reflectivity R is different. It is concluded that the bigger R is, the narrower the transmission window is. The relationship between fineness F and R is studied. It is concluded that the fineness increases rapidly at about 0.95, and then the basic principle of fiber grating is studied and analyzed by coupling mode theory. The coupled mode equations of uniform grating and chirped grating by transfer matrix method are solved directly, and the reflectance spectra of various gratings are simulated by using Matlab. Secondly, the characteristics of grating are studied by changing the values of parameter variables. The modulation depth of refractive index, the effective refractive index of uniform grating, the effect of chirped coefficient of chirped grating on the peak reflectivity, bandwidth and delay jitter, respectively. The effects of grating length, refractive index modulation depth, cavity length and effective refractive index on the reflectance spectrum are studied when the two gratings are identical. The grating length and refractive index modulation depth of the two gratings have different effects on the reflection spectrum at the same time. Then, aiming at the jitter at the top of the reflection spectrum of the chirped grating, the commonly used apodization technique is used to optimize the reflection spectrum. It is found that the bandwidth becomes smaller and the inclination increases after the toe is cut, and then the symmetrical toe is used to improve the above situation. It is found that the symmetrical toe has some compensation for the bandwidth and inclination, but there is still jitter at the top. The adoption of asymmetric toe cutting is further improved, The grating is divided into three sections. By studying the variation of Gao Si control parameter a and half full width before and after apodization, and the variation of average delay fluctuation before and after toe cutting, the optimal Gao Si control parameters of each segment are obtained as follows: a 1 / 8 a 2H 4A 3N 5, respectively. Simulation of chirped gratings. Finally, The optical clock signal at 40GHz is extracted by ordinary F-P cavity, and the reflectivity R of the plane mirror is 0.93U 0.990.999.The frequency domain and time domain diagram of the clock signal recovered by 0.999 are compared. It is concluded that the more fineness the recovery, the better the clock effect. But when the fineness is too high, the transmission window is very narrow, which will lead to the difficulty of alignment, and the optimization effect is not obvious. So we choose RP0.99 to continue the follow-up research. Because the single wavelength clock signal is only about 0.96 nm bandwidth, we first try to use the fiber grating F-P cavity to extract the single-wavelength clock signal. But the transmission window is not controllable, so this scheme is not feasible. Then the grating is used to filter the optical signal, but the reflection spectrum of the grating is not an ideal bandpass filter, so the signal entering the F-P cavity has jitter. The clock extraction effect is not satisfactory, and it is pointed out that the bandwidth of uniform grating is very difficult to reach 0.96 nm in practical application. Finally, the uneven top of the reflection spectrum of chirped grating is eliminated by the digitalization technique in Chapter 4th. According to the chirped grating characteristic in chapter 3, the peak reflectivity of 螖 neff=1*10-4 is increased by increasing the refractive index modulation depth to obtain a better recovery effect.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.11;TN253

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