Tunable Fano resonances via optomechanical effect and gain–loss ratio in coupled microresonators

Abstract

We propose a system consisting of two coupled optical whispering-gallery-mode (WGM) microresonators to investigate the Fano resonances of the output probe field. The WGM microresonators are driven coherently by a strong pump field and a weak probe field via tapered fibers (Peng et al 2014 Nat. Phys. 10 394). By making one of the resonators optomechanical and properly adjusting the coupling strength between the microresonators, we tune the Fano line shapes by varying the optomechanical strength. It is found that Fano line shapes appear on introducing optomechanical effects into the system. Interestingly enough, the gain-loss ratio in the proposed system has a key role in tuning a single Fano line shape to double. For the PT -symmetric phase, we investigate a more prominent double Fano line shape. The adjustment from single Fano line shape to double via the gain-loss ratio is the major part of this work. Our results can be used for all-optical switching and high-sensitivity sensing.

Multiple Fano Resonances in a Metal–Insulator–Metal Waveguide for Nano-Sensing of Multiple Biological Parameters and Tunable Slow Light

“…Unlike conventional Lorentz resonance with a symmetric lineshape, Fano resonance, which emerges when a broad continuous state is connected to a narrow discrete state, usually has a sharp and asymmetric lineshape. Due to the unique lineshape, small changes in the geometry or environment can significantly affect Fano resonance [5][6][7][8][9]. Electromagnetic waves known as surface plasmon polaritons (SPPs) are found solely between a metal and a nonconductor, at their intersection.…”

Manipulation of multiple Fano resonances in transmission spectra of a plasmonic structure with T-shaped and split-rectangular cavities

“…It results from the interference and coupling between a narrow discrete state and a broad continuum state [2][3][4]. Unlike the traditional symmetric resonance, the Fano resonance exhibits an ultra-sharp, asymmetric spectral line shape with the properties of high refractive index sensitivity (S), high figure of merit (FOM), and strong field enhancements [5,6]. Because of these properties, the Fano * Author to whom any correspondence should be addressed.…”