Research On Supercontinuous In High Nonlinear Photonic Crystal Fiber

Because of the dispersion and nonlinear effect, frequency spectrum will been broaden when ultra-short pulses propagate in nonlinear media, which is called the super-continuum(SC). As SC has widely spectrum range, strong stability, good performance characteristics of coherent, these characteristics make it be applied to many fields. Photonic crystal fiber(PCF) is a very effective medium for generating SC.Due to the advantages of flexibility of structure design and special mechanism of light transmission, PCF has many incomparable superiorities compared with traditional fiber.In this paper, evolution of a femtosecond pulse is modeled based on the nonlinear Schrodinger equation by predictor-corrector split-step flourier method when the pulse travels in the PCF. By using the tellurite glass, the PCF has high transmittance and nonlinear coefficient in infrared. The impacts of the fiber length,dispersion parameter, pulse peak power and pulse width on the SC generation are discussed respectively. The result shows that a SC spanning from 1330 nm to 3450 nm after 15 cm traveling distance when the PCF is pumped by a femtosecond pulse centred at 2μm and its peak power is 20 KW.A dual-wavelength pump source is obtained by second harmonic generation.Supercontinuum generation by dual-wavelength pumping in PCF with three zero-dispersion wavelengths is proposed. The spectrum extended from visible light to mid infrared. The impacts of the fiber length and pulse peak power on the spectrum are discussed respectively. It shows that a combined visible and infrared supercontinuum spectrum spanning from 690 nm to 3150 nm after 10 cm traveling distance when the fiber is pumped by two pulse centred at 1μm and 2μm simultaneously. The spectrum has good continuity and flatness.