Pulse trapping resulting from different polarized angles in birefringent photonic crystal fibers

摘要

We present a theoretical investigation of the nonlinear propagation of an optical pulse in a birefringent photonic crystal fiber (PCF). The strict coupled nonlinear Schroednger equations are solved numerically using a standard split-step Fourier algorithm. The phenomenon of pulse trapping is observed for different polarized angles except 0 degree and 90 degree, when the central wavelength of the input optical pulse is located in the anomalous dispersion region. With a single pulse which inclines from one axis launched into a birefringent PCF, the input pulse is split into two orthogonally components (signal and pump component) between the two orthogonally axes. The signal pulse suffers cross phase modulation by the pump (Raman shifted soliton) pulse and it is trapped and copropagates with the Raman soliton pulse along the fiber. A minimum trapping efficiency is obtained when the polarized angle is at 45°. For two complementary polarized angles, higher trapping efficiency can be obtained for smaller angle. As the input power of pulse is increased, the red-shift of the Raman soliton is considerably enhanced, leading to further red-shift of the trapped pulse to satisfy the condition of group velocity matching.