Graphene-integrated microring cavity for electronically controlled molecular fingerprinting

Area of Science:

• Photonics
• Nanotechnology
• Biomedical Engineering

Background:

• Microring cavities with whispering-gallery modes (WGMs) offer high quality (Q) factors and small mode volumes, enhancing light-matter interactions.
• Two-dimensional van der Waals (vdW) materials like graphene are promising for nanoscale light confinement in biosensing.
• Graphene's unique electronic properties allow for tunable optical responses.

Purpose of the Study:

• To propose and numerically investigate a novel hybrid microring cavity integrated with graphene.
• To demonstrate the capability of this hybrid cavity for molecular fingerprint retrieval.
• To explore the potential for chip-integrated, electrically modulated infrared spectroscopy biosensing.

Main Methods:

• Numerical simulations using the finite-difference time-domain (FDTD) method.
• Integration of graphene into a microring cavity to form a hybrid structure.
• Analysis of whispering-gallery modes (WGMs) and their response to biomolecular deposition.

Main Results:

• The hybrid cavity supports high-Q WGMs (Q factor up to 800).
• Resonant wavelengths are electronically tunable via graphene's Fermi level modulation across the infrared spectrum.
• Accurate broadband molecular fingerprint retrieval was achieved for a model biomolecule (CBP).

Conclusions:

• The proposed graphene-enhanced microring cavity enables sensitive, broadband, and electronically controlled infrared spectroscopy biosensing.
• This technology paves the way for miniaturized, chip-integrated biosensing devices.
• The hybrid cavity design offers a promising platform for next-generation molecular detection.