All-dielectric metasurfaces with high Q-factor Fano resonances enabling multi-scenario sensing

Area of Science:

• Photonics and Nanotechnology
• Biosensing
• Infrared Spectroscopy

Background:

• All-dielectric metasurfaces offer unique optical properties for sensing applications.
• High Q-factor resonances are crucial for achieving high sensitivity in refractive index and chemical sensors.
• Mid-infrared spectroscopy is vital for identifying molecular vibrations and chemical information.

Purpose of the Study:

• To propose and numerically demonstrate high Q-factor all-dielectric metasurface sensors.
• To investigate the sensing capabilities of symmetric and asymmetric tetramer metasurfaces for trace-amount molecules.
• To enhance sensitivity and enable non-destructive identification in the mid-infrared regime.

Main Methods:

• Numerical demonstration of all-dielectric metasurfaces with high Q-factor resonances.
• Utilizing light incident angular scanning for sensing trace molecules.
• Investigating asymmetric metasurfaces to induce quasi-bound states in the continuum (quasi-BIC) for Fano resonances.

Main Results:

• Symmetric tetramer metasurfaces show high sensitivity to refractive index changes and incident angle.
• Demonstrated huge absorbance enhancement (up to 10 dB) for molecules like protein A/G, 2, 4-DNT, and graphene in the mid-infrared (5.75–6.80 μm).
• Asymmetric tetramer metasurfaces exhibit multi-extremely narrow linewidth Fano resonances with a maximum sensitivity of 1.43 μm/RIU.

Conclusions:

• All-dielectric metasurfaces are excellent platforms for sensitive refractive index and chemical information sensing.
• The proposed sensors demonstrate highly enhanced performance for trace-amount biomolecules and materials.
• This work inspires the development of new high-sensitivity mid-infrared sensors for non-destructive identification.