| 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.
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