A cross-band quantum light source based on spontaneous four-wave mixing in a shallow-ridge silicon waveguide

To fully utilize the resources provided by optical fiber networks, a cross-band quantum light source generating photon pairs that one photon in a pair is at C band and the other is at O band is proposed in this work. This source is based on spontaneous four-wave mixing (SFWM) in a piece of shallow-ridge silicon waveguide. Theoretical analysis shows that the waveguide dispersion could be tailored by adjusting the ridge width, enabling the broadband photon pair generation by SFWM across C band and O band. The spontaneous Raman scattering (SpRS) in silicon waveguides is also investigated experimentally. It shows that there are two regions in the spectrum of generated photons by SpRS, which could be used to achieve the cross-band photon pair generation. A chip of shallow-ridge silicon waveguide samples with different ridge widths is fabricated, by which the cross-band photon pair generation is demonstrated experimentally. The experiment results show that the source can be achieve by dispersion-optimized shallow-ridge silicon waveguides. This cross-band quantum light source provides a way to develop new fiber-based quantum communication functions utilizing both C band and O band and extend applications of quantum networks.