Active Switching of Extremely High-Q Fano Resonances Using Vanadium Oxide-Implanted Terahertz Metamaterials

Superbound state in photonic bandgap and its application to generate complete tunable SBS-EIT, SBS-EIR and SBS-Fano

Bound states in continua (BICs) have high-quality factors that may approach infinity. However, the wide-band continua in BICs are noise to the bound states, limiting their applications. Therefore, this study designed fully controlled superbound state (SBS) modes in the bandgap with ultra-high-quality factors approaching infinity. The operating mechanism of the SBS is based on the interference of the fields of two phase-opposite dipole sources. Quasi-SBSs can be obtained by breaking the cavity symmetry. The SBSs can also be used to produce high-Q Fano resonance and electromagnetically-induced-reflection-like modes. The line shapes and the quality factor values of these modes could be controlled separately. Our findings provide useful guidelines for the design and manufacture of compact and high-performance sensors, nonlinear effects, and optical switches.

Temperature-controlled optical switch metasurface with large local field enhancement based on FW-BIC

Introduction: Many researchers have explored the bound states in the continuum (BICs) as a particular bound wave state which can be used to achieve a very high Q-factor. High-Q factor devices, typically based on the bound states in the continuum (BICs), are well used in the fields of hypersensitive biochemical sensors, non-linear effects enhancement, plasmon lasers, and hi-performance filtering. However, symmetrical-protected BIC is difficult to achieve experimentally high-Q factor because it strongly depends on the geometry and can be destroyed by any slight disturbance in the potential well.

Methods: Therefore, we proposed a parameter-adjusted Friedrich-Wintergen BIC based on the analysis model of time-coupled model theory, where the target system parameters can be tuned to achieve high-Q excitation.

Results: Moreover, considering the tunability and flexibility of the components in various practical applications, we integrate active materials into metasurface arrays with the help of external stimuli to achieve modulation of high-Q resonances. Our results demonstrate that an optical resonator based on FW-BIC can modulate the BIC state by changing the intermediate gap.

Discussion: The BIC state and the high-Q factor Fano resonance can be dynamically tuned by adding temperature-sensitive VO2 material.

A Review on Metamaterials for Device Applications

Metamaterials are the major type of artificially engineered materials which exhibit naturally unobtainable properties according to how their microarchitectures are engineered. Owing to their unique and controllable effective properties, including electric permittivity and magnetic permeability, the metamaterials play a vital role in the development of meta-devices. Therefore, the recent research has mainly focused on shifting towards achieving tunable, switchable, nonlinear, and sensing functionalities. In this review, we summarize the recent progress in terahertz, microwave electromagnetic, and photonic metamaterials, and their applications. The review also encompasses the role of metamaterials in the advancement of microwave sensors, photonic devices, antennas, energy harvesting, and superconducting quantum interference devices (SQUIDs).