| Photonic crystal fiber (PCF) is a new kind silica fiber with periodical structure in the cladding. It has many unusual properties compared to standard fibers, such as endless single mode operation, flexible tailorability of dispersion and modal area, high birefringence, high nonlinear effects etc. The adjustable properties of PCF suggest a lot of potential applications in the field of pulse compression, short wavelength soliton transmission, ultra-broadband continuum generation and nonlinear optics etc. In this dissertation, the nonlinear properties of PCF are studied. The main contents are listed below:1. The general concept of PCF is summarized systemically. The optical properties and applications of PCF are also analyzed.2. The physical processes of laser pulse propagation in fused-silica fibers are theoretically studied, focusing on the linear and nonlinear properties of optical fiber that alter the intensity of laser pulses. From the Maxwill's equation, the NLSE of the transmission of pico-second and femto-second optical pulses is deduced. Four-wave mixing effects generating from the interplay of several optical waves in PCFs are mainly discussed.3. The main methods of solving NLSE are studied. And the NLSE is solved by split-step Fourier method in this paper. The propagation of the femto-second pulse in PCFs' different dispersion regions is numerically simulated. Laser pulses with different wavelength and peak power in PCFs' different dispersion regions are simulated and analyzed. The explanation to the SC generation in PCF is given.4. Experimental investigation of SC generation based on the highly nonlinear PCFs is presented. A lot of new spectrums such as red light, yellow light, and green light are observed in the experiment. The mechanisms and conditions of SC generation are analyzed, the potential mechanism of SC is the result of the interplay of SPM, XPM, SRS, FWM and GVD et al.. |
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