Exceptional-point-enhanced nanoparticle sensor utilizing a linewidth broadening mechanism.

Area of Science:

• Non-Hermitian physics
• Optics and photonics
• Nanotechnology

Background:

• Exceptional points (EPs) in non-Hermitian systems offer unique properties for devices and sensing.
• Prior EP sensing research primarily focused on mode splitting, neglecting linewidth broadening.

Purpose of the Study:

• To explore nanoparticle detection using the linewidth broadening mechanism at EPs in a microdisk cavity.
• To compare EP-based sensing with diabolic point (DP) based sensing.

Main Methods:

• Constructed an EP by embedding two nanoholes in a microdisk cavity.
• Analyzed nanoparticle adsorption effects on transmission spectra linewidth.
• Calculated linewidth broadening at EPs and DPs.

Main Results:

• Achieved enhanced linewidth broadening for nanoparticle detection at EPs.
• Observed linewidth broadening exceeding frequency splitting due to nanoparticle adsorption.
• Demonstrated EP-based sensing significantly outperforms DP-based sensing.

Conclusions:

• Linewidth broadening at EPs provides a novel mechanism for highly sensitive nanoparticle detection.
• EPs in microcavities offer a promising platform for advanced sensing technologies.
• This work advances understanding of non-Hermitian physics and its applications.