Frequency and Polarization Characteristics of Correlated Photon-Pair Generation Using a Silicon Wire Waveguide

We report the frequency and polarization characteristics of correlated photon pairs generated in a Si wire waveguide (SWW). We confirmed that the bandwidth for correlated photon-pair generation was at least >2.8 THz. Moreover, we carried out a classical four-wave mixing experiment using strong pump and idler lights to estimate the bandwidth for correlated photon-pair generation. The results indicated that it is possible to generate photon pairs over a bandwidth as large as ~12 THz. We also showed that the generation efficiencies of the signal and idler photons for the horizontal polarization mode were much higher than those for the vertical polarization mode. This is probably caused by the large efficiencies in the group indexes and the effective cross-sectional areas for the two polarization modes. Furthermore, the bandwidth for the correlated photon-pair generation in the vertical polarization mode was ~±1 THz, and this was much narrower than that for the horizontal polarization mode. The difference between the bandwidths of the two polarization modes indicates that the SWW dispersion for the vertical polarization mode is significantly larger than that for the horizontal polarization mode. We then confirmed that the noise photons generated by spontaneous Raman scattering in an SWW were suppressed to below the detection limit of our setup.