| Supercontinuum(SC) generation in photonic crystal fibers(PCFs) has broad applications in various fields such as optical communication, spectroscopy, optical metrology and medicine. And it has been a subject of intense research in recent years. The dispersion profile can be varied along the fiber length in dispersion decreasing PCF, meanwhile the nonlinearity will be enhanced, which will broaden the spectrum range of SC. In this dissertation, SC generation in dispersion decreasing PCF is studied theoretically and experimentally. The main contents are given as follows:1. The physical mechanisms of the SC generation in optical fibers are described, and the efficts of fiber dispersion properties on the SC generation are analyzed. The numerical model and its solution methods for the SC generation in dispersion decreasing fiber are given.2. The dispersion measurement method based on Fourier transform is investigated. The dispersion curve of the test fiber can be obtained through only once measurement using this method. It is much simpler than traditional methods. The dispersion of a photonic bandgap fiber is measured with this method, and the experimental results are in well agreement with the numerical calculations within the effective wavelength range.3. SC generation in dispersion decreasing PCF with different structure parameters is researched experimentally. A sub-nanosecond pulse laser working at 1064 nm is used as the pump source. Compared with uniform PCF, the SC generated in dispersion decreasing PCF is broader. With optimum structure parameters, SC with spectral range from 427 nm to 1700 nm is demonstrated, and the fluctuation between 430 nm to 800 nm is about 5 d B.4. SC generation in dispersion decreasing PCF is studied numerically, and the impacts of fiber length, input and output end structure parameters are analyzed. Based on the simulation results, an optimum dispersion decreasing PCF for visible SC generation is designed. |
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