Electrical addressing of exceptional points in compact plasmonic structures

Area of Science:

• Photonics
• Plasmonics
• Non-Hermitian physics

Background:

• Exceptional points (EPs) are degenerate singularities in non-Hermitian systems, crucial for enhancing optical sensitivity.
• Previous research on EPs was largely confined to static photonic structures.
• Controlling interactions between resonant photonic modes is key to inducing EPs.

Purpose of the Study:

• To propose and experimentally demonstrate an electrically addressable exceptional point (EP) in a plasmonic structure.
• To investigate the electrical control of coupled plasmonic modes for EP realization.
• To explore the potential of EPs in compact, tunable integrated photonic devices.

Main Methods:

• Utilized a localized spoof plasmon structure supporting circulating plasmonic modes.
• Employed an angled metal line to perturb plasmonic modes and a varactor for electrical control.
• Performed numerical simulations to analyze eigenmodes and coupling, followed by experimental spectral measurements.

Main Results:

• Demonstrated simultaneous coalescence of the real and imaginary parts of eigenfrequencies via electrical tuning.
• Experimentally verified the coalescence of two resonant modes in both resonance frequency and linewidth.
• Showcased electrically addressable EPs in a compact, single-resonator plasmonic geometry.

Conclusions:

• Electrically addressable EPs have been successfully realized in a compact plasmonic structure.
• This work enables dynamic control over EP phenomena in plasmonic systems.
• The findings offer significant potential for developing highly functional and tunable elements in integrated photonic platforms.