| Over the past few years, successful fabrication of photonic crystal fibers and tapered fibers have extended fibers' applications to much broader fields such as frequency metrology, spectroscopy, optical coherence tomography, microscopy, etc. Their great potential in applications stems from their special and engineerable linear and nonlinear properties. Our research is focused on studying and manipulating the linear and nonlinear properties of photonic crystal fibers and tapered fibers, and demonstrating their applications in femtosecond science and technology with their unique properties.;We design and construct a CO2 laser tapering system and successfully use it to fabricate various kinds of tapered fibers. Using tapered single mode optical fibers, we demonstrate supercontinuum generation with larger than one octave spectral span. By applying the delayed pulse method to characterize the supercontinuum, we observe a strong dependence of the spectral coherence on the input wavelength, and then obtain a highly spectral coherent supercontinuum from 500nm to 1300nm by properly locating the input wavelength in the relatively deep anomalous dispersion region.;We study the high order soliton fission process that produces the supercontinuum. We show numerically and experimentally that the soliton fission process is extremely sensitive to the input state of polarization even in an isotropic nonlinear medium, which leads to a significantly different vector soliton fission scenario compared to the most commonly used scalar scenario. |
