Photonic crystal nano-cavities for enhancing zero-phonon line emission from nitrogen-vacancy centers in diamond

This paper presents designs of nano-cavity structures based on a photonic crystal in diamond in order to achieve high-efficiency collection of zero-phonon line (ZPL) photons emitted from the nitrogen-vacancy centers in diamond. The cutoff radius is calculated so as to ensure that the dual-resonances for both the pump and the ZPL photons could exist in the designed cavities. Our conceptual designs are demonstrated through simulations by finite-difference time-domain (FDTD) method. High Q for the pump (∼1.9148×105), strong enhancement of spontaneous emission in terms of Purcell factor (∼3812.1), and high coupling efficiencies for pump and for ZPL output (∼94.06% and 92.19% respectively) could be numerically obtained, which may make our designs applicable in quantum-optical information processing systems such as quantum nodes or quantum repeaters.

► Photonic crystal diamond nanocavities enhance spontaneous emission from N-V center.
► We utilize the dual resonances for the pump and zero phonon line modes.
► High Q, Purcell factor and coupling efficiencies were obtained numerically.
► Mode splitting accounts for the high coupling efficiencies for pump and the ZPL.
► The designs may be applicable to quantum-optical information processing systems.