We realize the correlated photon pair generation at 1.5μm by spontaneous four-wave mixing in high nonlinear
microstructure fibre with a length of 25m, showing that high nonlinear microstructure fibres have great potential in
bright, high efficiency and compact sources of correlated photon pairs at 1.5μm.
Spontaneous parametric down-conversion in two-dimensional photonic crystal made of semiconductor material with large quadratic nonlinear susceptibility is proposed to generate polarization entangled photon pairs. On one hand, the large quadratic nonlinear susceptibility of AlGaAs crystal insures the high nonlinear conversion efficiency; on the other hand, the abnormal dispersion property of two-dimensional photonic crystal causes the satisfaction of the phase-matching condition. In particular, the dispersion property sensitively depends on the structure of photonic crystal. Then the walk-off between the down-converted photons with orthogonal polarizations can be minimized through appropriate structure parameter design; hence compensation measures to mitigate labeling effect on polarization entangled photon pairs can be eliminated.
Build-up process of the broadband continuous-wave supercontinuum Raman lasing (CWSCRL) in a fiber ring cavity is reconstructed theoretically through simulation based on the generalized nonlinear Schrodinger equations in the spectral domain. The physical mechanism of the CWSCRL is revealed as a combined effect of light amplification by stimulated Raman scattering and spectral broadening by four wave mixing in the view of the spectral domain. Detailed analysis as well as experimental confirmation shows that broad and flat spectrum can be achieved mainly by assigning the pumping wavelengths so that the first Raman Stokes wavelengths occur at both sides of the zero dispersion wavelength of the highly nonlinear dispersion-shifted fiber in the ring cavity, while optimization in pump power also matters. Different time structures of the Raman lasing are determined by the dispersion at the first-order Raman Stokes light wavelengths.