【作者】 杨四刚；

【导师】 谢世钟；

【作者基本信息】 清华大学 ， 电子科学与技术， 2007， 博士

【摘要】 光子晶体光纤(PCF),可以实现极大的折射率调制和高度灵活的折射率分布,可以满足色散补偿光纤和高非线性光纤对大折射率调制的要求。基于PCF技术的色散补偿光纤和高非线性光纤具有十分优异的色散特性和非线性特性,是目前研究的热点问题。论文首先研究了仿真PCF的两种算法:时域有限差分方法(FDTD)和频域有限差分方法(FDFD)。以这两种方法为核心算法,开发了光子晶体光纤仿真软件。该软件界面友好,操作简单,通用性强,可以仿真任意结构的光子晶体光纤。运用所开发的仿真软件,对PCF进行了几种理论设计和仿真。首先,利用FDTD研究了带隙型PCF,获取了光纤的导引频率、泄漏损耗和模场分布。其次,提出了一种宽带色散补偿光子晶体光纤的设计。通过在内包层引入一圈柚子形空气孔,大大改善了光纤的色散性能,其色散曲线在至少60nm带宽内随波长线性变化,解决了双芯PCF负色散带宽窄的问题。论文还提出了一种色散可调的PCF。通过往单模PCF的特定空气孔中选择性注入聚合物,改变光纤的传输特性,使得光纤具有大负色散,且其色散可随注入聚合物折射率的改变被调节。论文介绍了关于一种大模场面积、大负色散的光子晶体光纤从理论设计、实验制作、色散测试以及模场测试的全过程。首先设计出了一种符合光纤拉制工艺要求的大模场面积、大负色散的PCF。进行了光子晶体光纤的实验拉制。对拉制出的光纤的测试表明,该PCF同时具有大模场面积和大负色散的特性。开发出了一套高分辨率、大动态范围的光纤模场测试系统。利用该系统对制作的PCF的模场进行了测试,研究了其模场随波长演变规律。基于国产的高非线性PCF进行了慢光的研究。首先解决了高非线性PCF与单模光纤的焊接难题。测试了该高非线性PCF的受激布里渊增益特性。应用该PCF进行了慢光的研究。通过使用50米高非线性PCF,实现了最大半个脉冲宽度的时间延迟。在实验中还发现脉冲的延迟时间随增益呈指数增加的现象。更多还原

【Abstract】 Photonic crystal fiber (PCF) can have very large refractive index modulation and very flexible index profile. It just meets the requirement on large index modulation in dispersion-compensating fiber(DCF) and high nonlinear fiber. PCF-based DCFs and high nonlinear fibers have outstanding performance in chromatic dispersion and nonlinearity respectively, which have attracted much attention.To simulate PCF, the dissertation studies two modeling methods which are Finite Difference Time Domain (FDTD) method and Finite Difference Frequency Domain (FDFD) method. Based on the two methods, a PCF simulating software is developed. The software is very friendly in the interface, very easy to use and can simulate all kinds of PCF profile.Several theoretical designs and simulations have been carried out by using the software. First, a band-gap guiding PCF is investigated by FDTD and the frequency of the guiding mode, the leaky loss and the mode field profile of the fiber are obtained. Secondly a broad band dispersion-compensating PCF is proposed. By introducing a ring of large grapefruit holes in the inner cladding, the dispersion performance of the dual core PCF can be improved greatly. The chromatic dispersion of the fiber demonstrates linear evolution with wavelength in a bandwidth of more than 60 nm. Thirdly, a tunable dispersion-compensating PCF is proposed. When a specific ring of air holes in a single mode PCF is filled with index tunable polymer, the propagation mechanism of the PCF is changed and the chromatic dispersion of the PCF is changed to be high negative. Moreover the chromatic dispersion of the PCF can be tunable when the refractive index of the filled polymer is changed.The dissertation presents a whole research process concerning a PCF with large mode area and high negative dispersion on the theoretical design, experimentally fiber-drawing fabrication and the measurements of the chromatic dispersion and the mode field of the fiber. At first, a PCF with large mode field area and high negative dispersion is designed theoretically based on the condition of the practical fiber drawing. And then the PCF is drawn experimentally. The measurement results on the fabricated PCF demonstrate that the fiber has large mode field area and high negative dispersion simultaneously. To study the mode field of the fabricated PCF, a fiber mode field measurement system with high resolution and large dynamic range is developed. The mode field of the fabricated PCF is tested and the evolution of the mode field with wavelength is investigated.A slow light experiment based on Stimulated Brillouin Scattering (SBS) in a homemade high nonlinear PCF is demonstrated. Low loss splicing between the high nonlinear PCF and a single mode fiber is realized. The Brillouin gain characteristic of the high nonlinear PCF is tested and a slow light experiment is carried out based on the PCF. Up to 1/2 pulse width delay is achieved in only 50-m PCF. It also demonstrates that the delay time grows exponentially with the Brillouin gain.更多还原