Research On The Generation And Influential Factors Of Dispersive Wave In Photonic Crystal Fibers

Dispersive wave generation is the phenomenon that optical pulses are perturbatedby high-order dispersion and nonlinear effects and the energy is radiated whenpropogating in nonlinear media. It is one of the main physical mechanisms ofsupercontinuum generation, and it has important applications in many fields. Photoniccrystal fiber has some unique characteristics compared with the conventional fiber. Itinjected new vitality for the researched field of nonlinear fiber optics. The dispersivewave generation in photonic crystal fiber is a fundamental problem of nonlinear optics,and is also a very complex nonlinear process, which is affected by many factors andhas become a research hotspot in recent years. The generation and influential factorsof dispersive wave in photonic crystal fiber are studied in this thesis. The mainresearch contents are listed below:Firstly, based on the nonlinear Schr dinger equation followed by optical pulsespropagating in photonic crystal fiber, the generation and influential factors ofdispersive wave in photonic crystal fiber are analyzed. The dispersive wavegeneration in photonic crystal fiber should meet the phase-matching condition, andbefore the dispersive wave generation, the spectrum should have sufficient width tobetter achieve phase matching. For the position of the dispersive wave generation, thedispersive wave is blue-(red-) shifted when the third-order dispersion of the photoniccrystal fiber is positive(negative). The wavelength of red-shifted dispersive wavebecomes longer with the increasing of the second zero-dispersion wavelength. Andthe blue-shifted dispersive wave becomes shorter with the increasing of the pumppulse peak power. For the control efficiency of dispersive wave generation, theefficiency of blue-shifted wave generation is improving as the pump pulse peak powerbecomes greater, and the initial positive(negative) frequency chirpincreases(decreases) the efficiency of blue-shifted dispersive wave generation. Thelonger of the center wavelength of pump pulse, the higher efficiency of red-shifteddispersive wave generation.Secondly, the computer program about two cascaded fibers has been improved,and the generation of dispersive wave in the cascaded fibers has been studied. Wepresent here spectrally smooth, highly broadband mid-infrared supercontinuum in thecascaded single mode fiber and highly nonlinear SF57photonic crystal fiber. The simulation results show that the amplification of dispersive wave is the main physicalmechanism of supercontinuum generation. It is necessary to optimize the length of thesecond stage fiber to get better flat supercontinuum. In addition, the red-shifteddispersive wave will be further broadened towards long-wavelength direction whenthe pump peak power is greater.Thirdly, the generation of dispersive wave in photonic crystal fiber with threezero-dispersion wavelengths is numerically studied. As the exist of the thirdzero-dispersion wavelength, the photonic crystal fiber with three zero-dispersionwavelengths has two anomalous dispersion regions, and has a wide phase-matchingregion. The results show that not only both blue-and red-shifted dispersive waves aregenerated in the two normal dispersion regions of the photonic crystal fiber, but alsodispersive wave soliton is generated in the low-frequency anomalous dispersionregion. Furthermore, it is found that the dispersive wave soliton with a higherefficient conversion contains most of the pump pulse energy, and it further radiatesblue-shifted dispersive wave in high-frequency normal dispersion region.