【作者】 李善甫；

【导师】 文双春；

【作者基本信息】 湖南大学 ， 通信与信息系统， 2006， 硕士

【摘要】 超高速全光开关是实现超高速光通信的一项重要关键技术。光子晶体光纤是近年来提出来的一种全新的光纤,它具有传统光纤所无法比拟的特殊的光学特性,如无截止单模、可控色散以及丰富的光学非线性等特性,在全光通信领域具有广阔的应用前景,已成为光纤通信领域的一个研究热点。采用脉冲俘获在光子晶体光纤中实现光开关能有效的提高光开关的响应速率,同时光开关还具有色散可控、俘获率高等特点。本文研究了光子晶体光纤中的脉冲俘获现象,以及基于脉冲俘获的光开关的基本原理和特性。取得的主要成果如下:第一,光子晶体光纤中脉冲俘获现象受多种因素的制约,理论分析十分复杂,数值模拟成为重要的分析手段。我们基于光子晶体光纤中光脉冲传输的理论模型自主开发了能模拟基于脉冲俘获实现光开关的计算机程序,与文献报道的理论和实验结果进行了比对,考核了程序计算结果的正确性。第二,研究了高阶色散、自陡峭、受激喇曼散射等各种高阶效应对光子晶体光纤中脉冲俘获的影响。结果表明,只有当抽运脉冲处于反常色散区、信号脉冲处于正常色散区时才能形成脉冲俘获现象,被俘获的信号脉冲频谱蓝移、抽运脉冲频谱红移;不考虑受激喇曼散射影响时脉冲俘获现象将消失。第三,分析了光子晶体光纤中基于脉冲俘获的超高速光开关的特性。数值模拟结果表明,增大抽运脉冲的初始功率,发生俘获的两个脉冲的频移将更加明显;抽运脉冲俘获信号脉冲串中的任何一个信号后,随着传输距离的增加,将不会影响到其它信号脉冲的传输特性;超高速光开关的响应速率受俘获率的制约,当其响应速率超过某一特定值时,信号脉冲的俘获率下降,同时会影响到下一个信号脉冲。为提高光开关的响应速率,必须缩短光子晶体光纤的长度或增加抽运脉冲的初始功率。更多还原

【Abstract】 Ultrafast all-optical switching is an important technique in future ultrahigh speed optical communication systems. Photonic crystal fibers (PCFs) have recently attracted significant attention because of their specifically controlled dispersion properties and their great potential applications in the fields of optical telecommunication,Therefore, the optical properties of a PCF differ remarkably from those of standard fibers. Ultrafast all optical switching by use of pulse trapping has high repetition frequency, high trapping efficiency and controlled dispersion properties The properties of ultrafast all optical switching by use of pulse trapping are analyzed. The main research results are listed below:Firstly, the propagation of pulse trapping in PCFs is limited by many physical factors, and the theoretical analysis is very complicated, so numerical simulation becomes crucial research methods. Based on the physical model of optical pulses propagation in PCFs, we have independently developed the computer program which can simulate the process of linear and nonlinear propagation of optical pulses. Compared with the experimental and theoretical results reported in literatures, the validity of the computation results of our program is confirmed.Secondly, an generic expression for pulse trapping which includes the influence of higher-order effects such as higher-order dispersion (HOD), self-steepening (SS), stimulated Raman scattering (SRS) etc. The numerical results show different phenomena are observed depending on whether the wavelength of the signal pulse is located in the normal or the anomalous dispersion region. In particular, it is found that the phenomenon of pulse trapping occurs when the signal wavelength is located in the normal dispersion region while the pump wavelength is located in the anomalous dispersion region, the pump pulse is red-shifted ,the trapped pulse is blue-shifted. This phenomenon is not observed when the effect of Raman scattering is not active.Thirdly, the characteristics of ultra-fast all optical switching by use of pulse trapping are analyzed. Numerical simulations show as the input peak power of the pump pulse is increased, the red-shift of the Raman soliton is considerably enhanced with the simultaneous further blue-shift if the trapped pulse to satisfy the condition of group velocity matching. It is interesting to note that although the other pulses are also overlapped with the soliton pulse, they are not trapped. The trapping efficiency更多还原