Enhanced second-order sideband generation and slow–fast light via coupled opto- and magnomechanical microspheres

In this research, we investigate second-order sideband generation (SSG) and slow–fast light switching using a hybrid system comprised of two coupled opto- and magnomechanical microspheres, namely a YIG sphere and a silica sphere. The YIG sphere hosts a magnon mode and a vibration mode induced by magnetostriction, whereas the silica sphere has an optical whispering gallery mode and a mechanical mode coupled via optomechanical interaction. The mechanical modes of both spheres are close in frequency and are coherently coupled by direct physical contact between the microspheres. We use a perturbation approach to solve the Heisenberg–Langevin equations, offering an analytical framework for transmission rate and SSG. We demonstrate that the transmission rate and SSG are strongly dependent on the magnomechanical, optomechanical, and mechanical–mechanical coupling strengths (MMCS) between the two microspheres. The numerical results show that increasing the MMCS can enhance both the transmission rate and SSG efficiency, resulting in a gain within our system. Our findings, in particular, reveal that the efficiency of the SSG can be effectively controlled by cavity detuning, decay rate, and pump power. Notably, our findings suggest that modifying the system parameters can alter the group delay, thereby regulating the transition between fast and slow light propagation, and vice versa. Our protocol provides guidelines for manipulating nonlinear optical properties and controlling light propagation, with applications including optical switching, information storage, and precise measurement of weak signals.