Efficient Coupling of Single Photons into Tilted Nanofiber Bragg Gratings

We report a new gateway towards the light-matter interaction of spontaneous emission from a quantum emitter (QE) in optical nanofiber (ONF) based on nanocavities tilted by some angle with respect to the plane of the fiber cross-section. This structure is designed by three-dimensional finite-difference time-domain simulations to enhance the spontaneous emission decay rate from a QE and maximize the coupling efficiency into the fiber-guided modes. Here, we systematically analyzed the polarization-dependent spontaneous emission characteristics of QE and cavity characteristics of the proposed structure. We show that the coupling efficiency from single emitters can reach as high as ~ 90% with the Purcell factor can be as high as ∼ 65. The results show a 10-fold enhancement factor from a QE in the cavity center compared with the cavity surface. The tilted angle can be optimized to get more transmission and coupling efficiency. This tilted structure has a high Q-factor of ~ 1000 and a low mode volume of ~ 0.56 μm³, with a maximum degree of polarization of the single photons has been calculated as high as 96%. For the quantum information and quantum photonics application, this system attracts researchers to a new direction in the quantum world.