Nanocavity plasmonic device for ultrabroadband single molecule sensing

Area of Science:

• Photonics and Plasmonics
• Terahertz (THz) Spectroscopy
• Nanophotonics

Background:

• Plasmon polariton photonic crystals offer unique light-matter interaction properties.
• Terahertz regime presents opportunities for novel sensing and communication technologies.
• Existing photonic crystals often face limitations in sensing volume and bandwidth.

Purpose of the Study:

• To design and simulate a novel metal-dielectric-metal plasmon polariton photonic crystal.
• To investigate the terahertz bandgap and defect-induced cavity properties.
• To evaluate the sensing capabilities, including sensing volume and Purcell factor.

Main Methods:

• Utilized three-dimensional finite-difference time-domain (FDTD) simulations.
• Designed a metal-dielectric-metal sandwich structure integrated with a periodic lattice.
• Introduced a defect to create a resonant cavity within the photonic crystal.

Main Results:

• Demonstrated a clear bandgap in the terahertz regime.
• Achieved a cavity with a quality factor of 23.3 at 3.45 micrometers.
• Observed an extremely large Purcell constant (4.8x10^6) due to an ultrasmall sensing volume (15 zeptoliters).
• The structure exhibits a broad bandwidth of approximately 7 THz.

Conclusions:

• The proposed plasmon polariton photonic crystal shows significant potential for high-performance sensing applications.
• The large Purcell constant combined with a broad bandwidth offers high specificity and tolerance to environmental changes.
• This design paves the way for advanced terahertz devices with enhanced spectral fingerprint detection capabilities.