Second-harmonic generation via micro ring resonators for optimum entangled photon visibility

An analysis of a new technique for quantum key distribution (QKD) using the entangled photon within a micro ring resonator is presented. The Kerr nonlinear type of light in the micro ring resonator induces the nonlinear behavior known as chaos within the device, where the superposition of the chaotic signals via a four-wave mixing type introduces the clear second-harmonic pulses. The generation of clear second-harmonic pulses is achieved by controlling the appropriate ring parameters. When the polarization control devices are applied into the system, the optimal entangle photon visibility is obtained. The condition for long-distance link is discussed, where the optimal entangled photon visibility in term of Bell's states is described.