Active control of single-photon spontaneous emission out-coupling enhancement by rotation modulation of hyperbolic metamaterials

Controlling the rate and direction of spontaneous emission is critical for quantum technologies such as single-photon sources and secure communications. We propose a tunable nanophotonic device that modulates spontaneous emission by rotating the optical axis of a hyperbolic metamaterial (Au-SiO₂) at room temperature. Analytical and numerical studies demonstrate that rotation alters the local density of states, enabling dynamic emission rate control without structural changes. The device's performance depends on the metal filling fraction, rotation angle, and wavelength, allowing spectral flexibility. As a proof of concept, we design a system that efficiently out-couples emission into a nano-waveguide. This approach provides a simple, geometry-independent method to switch emission on/off, advancing practical quantum photonic devices. The work opens avenues for applications in quantum optics, sensing, and on-chip quantum networks.