The Oretical And Experimental Investigation On Two Zero-Dispersion And Nonlinearity Of Photonic Crystal Fibers

The study of dispersion and nonlinearity of photonic crystal fibers are two important fields in the research of photonic crystal fibers. And the study of nonlinearity of photonic crystal fibers with two zero-dispersion is becoming the most important one of the research of photonic crystal fibers. The two zero-dispersion and nonlinear properties of photonic crystal fibers are investigated respectively. The main results are summarized as follows:Firstly, the dispersion and nonlinear coefficients of several different PCFs are numerical simulated by Improved Fully Vectorial Effective Index Method (IFVEIM). The relation between the structure parameters and dispersion, the structure parameters and nonlinear coefficient are analyzed. With the variety rule, the two zero-dispersion and nonlinearity of photonic crystal fibers with two zero-dispersion are investigated.Second, a kind of photonic crystal fiber with two zero-dispersion wavelengths is investigated in use of multipole method by tailoring the pitch and the diameter of cladding hole. The slip-step Fourier method is used to numerically simulate the ultrashort pulses'transmission in this fiber. As the result of transmission, the mostly energy between the two zero dispersion wavelength is transformed into the two spectral lobes. The efficiency of pumping is so high that more than 99% energy of input is transferred into the two spectral lobes. The two spectral lobes are very flat, they fluctuate with wavelength and insensitive to pulse energy as well as chirp of pump pulse, thus resulting in the high stability of spectra and making it have wide applications.The final, it is demonstrated that femtosecond pulses transmit in a highly nonlinear PCF manufactured by our group. The frequency conversion in abnormal dispersion region of a highly nonlinear PCF at the different power and wavelength are researched by Femtosecond Laser Pulses. Analyze the influence of central wavelength and power of input pulses on the output spectrum. When the central wavelength of input pulses is different, the frequency conversion follows the changes, which is bigger as the central wavelength of input pulse is more near to the zero-dispersion wavelength. Especially when central wavelength of input pulses is 760 nm, the central wavelength of anti-Stokes wave is 465 nm, the intensity of anti-Stokes is eight times more than the intensity of residual pump energy, and the transform-efficiency exceeds 90%.