Experimental Research On Supercontinuum Generation In Tapered Microstructure Fiber Pumped By Femtosecond Pulse

Microstructure fiber based on silicon has tunable dispersion, designable nonlinear, highly birefringence and no cut-off mode. It is interest in a very wide range of applications as a new generation of medium for optical transmi ssion. By tapering, the downtapering and taper waist of microstructure fiber make the dispersion change gradually, blueshift the zero dispersion wavelength, increase the nonlinearity and optical power density, which plays an important role in researching o n the supercontinuum generation of microstructure fiber. This paper reviews the research of supercontinuum generation in tapered microstructure fiber at home and abroad in detail, and experimently studys on the basic characteristics and supercontinuum generation of tapered microstructure fiber fabricated by heating and stretching. The main contents are as follows:First, the background and significance, the theory, experiment and application of tapered microstructure fiber at home and abroad are briefly introduced. The linear fused taper and parabolic taper of the tapered microstructure fiber are introduced detailedly.Next, the microstructure fiber and the Yb³⁺-doped microstructure fiber are tapered by “fast and cold”. The best tapered condition of the used microstructure fiber and Yb³⁺-doped microstructure fiber is explored experimentally. The single and cascaded taper are fabricated in satisfing with the gradient conditions of tapered section. The the fiber parameters are determined conveniently. The effective refractive index, mode field area and dispersion characteristics of the tapered microstructure fiber are calculated theoretically.Once more, the supercontinuum of different tapered lengths and cascaded taper microstructure fiber pumped by femtosecond pulse of different center wavelength, different power are studied experimentally. The supercontinuum is explained detailedly combined with the dispersion and nonlinear of the tapered region, and then gets the best conditions of ultra wideband continuous spectrum.Finally, the absorption emission characteristics and supercontinuum generation before and after tapering of the Yb³⁺-doped microstructure fiber by femtosecond pulse of different center wavelength, different power is studyed. The spectral characteristics are explained by the emission of Yb³⁺ ion and the nonlinearity of fiber itself. And an innovative method is proposed for the application of earth ion s doped microstructure fibee in the supercontinuum generation.