【作者】 王秋国；

【导师】 杨伯君；

【作者基本信息】 北京邮电大学 ， 电磁场与微波技术， 2009， 博士

【摘要】 本论文是围绕以下项目展开的:国家自然科学基金项目《光子晶体光纤及其在量子通信中的应用的研究》（60578043）,北京市共建项目《光子晶体光纤及WDM系统中若干重要技术的研究》（XK100130637）和《现代通信系统中新型探测技术与接收模块的研究》（XK100130737）。结合课题的要求和主要目标,在对光子晶体光纤（PCFs）传输特性研究的基础上,对其应用展开研究。由于光子晶体光纤（PCF）在色散与非线性方面具有普通单模光纤没有的特性,它能在一个较宽的频带内保持单模特性,它的零色散点可以在800nm～1600nm之间变化,它的纤芯可以比较小而产生较大的非线性,γ值在850nm处可达到240W^-1.km^-1。利用它做成有源器件,在光通信中,特别是波分复用系统中是很有前途的,如宽带色散补偿、光脉冲压缩、波长变换、超连续谱产生和光放大器等。本文对光子晶体光纤在光纤通信系统中的应用:如光纤参量放大器技术、波长变换技术及超连续光源方面的应用进行了理论与实验研究。光纤参量放大器是即掺铒光纤放大器（EDFA）、拉曼放大器（RA）及半导体光放大器（SOA）后出现的一种光放大器,光纤参量放大器以其高增益、宽带宽等优点,应用潜力非常广泛,发展潜力巨大;波长变换则是全光网及光交换过程中的关键技术之一,利用这一技术可以实现在线开关等全光操作过程;超连续光源则是基于超连续谱的宽带波长可任意提取的超宽带光源,它提供了一种在很宽的光谱范围内产生超短脉冲的非常经济的技术和方法,从而作为新一代多载波光源受到业界广泛关注。本文的主要工作与创新点（黑体部分）介绍如下:1.利用色散平坦光子晶体光纤构建了光纤参量放大器,完成了光子晶体光纤中的参量放大器实验,实验中观测的增益带宽为28nm。理论上分析了光子晶体光纤参量放大器的增益特性、相敏特性和带宽特性,数值模拟分析了光子晶体光纤的非线性系数、色散、泵浦功率以及光纤长度等参数对参量放大的增益和带宽的影响。2.利用光纤中的四波混频进行了波长变换的实验研究,成功进行了1550nm波长附近的波长变换,实际测量波长变换带宽为3dB带宽为28nm,最高转换效率为-26dB,同时也实现了全光频移型的光开关操作。3.详细介绍了光子晶体光纤的几个突出优点:单模传输特性、高非线性效应、可控色散特性和双折射特性。在此基础上,讨论了光子晶体光纤在有源器件中的应用,同时介绍了它在各应用领域中的优势。4.利用脉宽为1.6ps脉冲,以50MHz被动锁模光纤环激光器为光源,在色散平坦光子晶体光纤中进行超连续谱产生的实验,当泵浦平均功率为26mW时,经过光子晶体光纤后得到20dB带宽为240nm的超连续谱。同时,系统分析了自相位调制、四波混频和受激拉曼散射等因素对光子晶体光纤中超连续谱产生的影响。5.以色散平坦光子晶体光纤为非线性介质,利用光纤的非线性效应,进行了飞秒脉冲产生超连续谱的实验。激光器产生120fs的激光脉冲,经一段约1米和的普通单模尾纤被展宽为689fs,利用此光源,以波长1550nm为中心波长,获得了20dB谱宽达480nm的超连续谱。6.在飞秒脉冲在色散平坦光子晶体光纤产生超连续谱的基础上,利用阵列波导光栅对超连续谱进行切处滤波,在1550nm波长附近,实现了32波长的飞秒脉冲输出,这种光源可以用于WDM系统的多信道传输过程,也可以作为波长可调的多波长飞秒脉冲激光器使用,有良好的利用价值。更多还原

【Abstract】 The works of this dissertation are supported by the National Natural Science Foundation Project "Photonic crystal fiber and its application in quantum communication research" （60578043） , the Foundation Project from the Education Commission of Beijing " A number of important research of Photonic Crystal Fiber and Its Application in WDM system" （XK100130637） , and "The research of New detection technologies and receiver module in Modern communication system （XK100130737） ".Combined with the requirements of the subject and the main objective, on the basis of the research of transmission characteristics of photonic crystal fibers （PCFs）, we Study of its application. As far as photonic crystal fiber is concerned, it is the fiber with a periodic microstrucure in air-glass. Compared with conventional single-mode fiber, PCF has some unique characteristics such as controllable dispersion and high nonlineatity. It can support endlessly single mode over a broad spectral range, as well as the zero-dispersion wavelength can vary from 800nm to 1600nm. PCF has high level of nonlinieatity due to the small core diameter, and values as high asγ=240W^-1.km^-1 at 850nm have been reported. Since the first PCF is invented in 1996, it has gained intense attention. Active devices based on PCF can expect a series of new applications in optical communication such as broadband dispersion compensation, optical pulse compression, wavelength conversion, supercontinuum generation and optical amplification. In this paper, we study the applications of PCF in optical communication such as fiber-optic parametric amplifier, wavelength conversion and supercontinuum light source technology. Fiber-based optical parametric amplifier is a new optical amplifier after Raman amplifier and the Erbium-doped fiber amplifier （EDFA）. Optical parametric amplifier has a wide range of potential applications with its high-gain, wide bandwidth, etc. Wavelength conversion is one of the key technologies in all-optical networks and optical switching. And supercontinuum light source has a ultra-broadband, it provides us the techniques and methods to get ultrashort pulses over a large range of wavelength, it has been widely concerned in recent years. The main contents and achievements of this dissertation are as follows.1. Using a 40m long dispersion flattened photonic crystal fiber, we propose an OPA based on PCF. The results show that the gain bandwidth is 28nm. And the gain characteristics, phase-sensitive property and bandwidth of optical parametric amplifier （OPA） based on PCF are addressed theoretically. The relationship between the properties of PCF, such as nonlinearity and dispersion, and characteristics of OPA are analyzed.2. Wavelength conversion based on four-wave mixing is studied experimentally. Wavelength conversion around 1550nm is achieved, the maximum conversion efficiency and the 3 dB band is about -26dB and 28nm respectively.3. Several prominent merits of PCF, such as property of single mode transmission, high nonlinearity, controllable dispersion and birefringence are systematically reviewed. Also, applications of PCF in active devices and potential advantages are introduced.4. By using 50MHz mode-locking fiber ring laser, Supercontinuum is obtained from dispersion-flattened PCF. The bandwidth of 240nm （at 20dB level） is achieved by launching 1.6ps pulses into a section of PCF. Moreover, the effects to the spectral broadening of SPM、FWM and SRS are analyzed. 5. By using passively mode-locking fiber ring laser, SC is obtained from dispersion-flattened PCF. The results show that bandwidth of 480nm （at 20dB level） can be achieved by launching 689fs pulses into a section of PCFs.6. Based on a femtosecond pulse pump power, we achieve a spectrally sliced pulse source which utilizes supercontinuum generated in a dispersion-flattened PCF and spectral slicing in an arrayed waveguide grating. All 32 channels exhibit almost constant pulsewidth and excellent noise properties. This pulse source can be used in WDM system, and also can be used as a wavelength turnable femtosecond pulse laser.更多还原