Novel e-SIL with embedded cone structure for the enhancement of photon collection efficiency from nitrogen–vacancy center in diamond

We present the design and theoretical simulation of a nano-range optical structure with an elliptical solid immersion lens (e-SIL) in a rectangular diamond substrate containing nitrogen–vacancy (NV) center in diamond. We have varied the numerical aperture of the objective lens and collected photons with a maximum collection efficiency of ∼88% for NA=1. The far field variations have been studied over a wide range of emission spectra of nitrogen–vacancy center in diamond. This highly efficient single-photon emitter has a wide range of applications in the field of nanoscale magnetic sensing and quantum information devices. •Nanoscale e-SIL embedded with cone structure diamond optical waveguide is proposed.•PCE reaches 88% when the NA is 1.•PCE is insensitive to the position of NV center within 50 nm inside the waveguide.•Highly-directional photon emission is obtained.•Tolerance to fabrication error made this optical waveguide design unique.