The Study Of Photonic Crystal Fiber And Supercontinuum Generation In It

Supercontinuum source have found many applications in areas such as opticalcommunications, spectrum metrology and biomedicine. Photonic crystal fiber is a preferredchoice to generate ultra-broadband spectrum for its outstanding advantages of highlynonlinear photonic crystal fiber and the flexibility to adjust the dispersion. As fiber lasersdevelop, ytterbium-doped fiber laser with compact structure, high stability, low maintenanceand high efficiency is best choice of the pump source for flat supercontinuum. However, thevisible light of high frequency, which is away from the wavelength of the laser and thezero-dispersion wavelength of fiber, is difficult to generate. So we call it “blue-ray defects”.Researchers at home and abroad focus on the goal of how to achieve a flat supercontinuumcovering the visible under lower power.Therefore, the study of dispersion characteristics and nonlinear characteristics ofphotonic crystal fiber and their effects on supercontinuum generation, design of new highlynonlinear fiber structure and improved fiber preparation becomes more and more importantThis thesis introduces the theory of the transmission of the light pulse in a nonlinear mediumand the nonlinear effects that are responsible for the generation of supercontinuum. Theprocess of supercontinuum generation is displayed in detail. Then the study analyzed howfiber structure parameters, chemical parameters and pump conditions, such as the pumpwavelength, power and pulse width, affect spectral broadening. A method to expandspectrum optimally is put forward according to simulation results. Finally, a series ofexperiments is carried out including uniform fiber, zero dispersion wavelength decreasingfiber, fibers with different core diameters and multi-core fibers. The spectrum has extendedto the blue and flat continuum covering406.1-671.8nm was generated. Our results indicatethat zero dispersion wavelength decreasing fiber with GeO2doped may open the way toultra-broadband SC sources for its potential in improving the group index.