Graphene-integrated microring cavity for electronically controlled molecular fingerprinting

• Dazhi Du, qing zhang, and Zhi-Hong Zhang
• received 01/22/2024; accepted 04/19/2024; posted 04/22/2024; Doc. ID 519693
• Abstract: Microring cavities supporting whispering-gallery modes(WGMs) have an exceptionally high-quality factor (Q) anda small mode volume, greatly improving the interactionbetween light and matter, which has attracted greatattention in various micro/nanoscale photonic devicesand potential applications. Recently, two-dimensional vander Waals (vdW) materials like graphene have emergedas a potential platform for next-generation biosensing byenabling the confinement of light fields at the nanoscale.Here, we propose a novel approach to achieve molecularfingerprint retrieval by integrating graphene into amicroring cavity, and conducting numerical simulationsusing Finite-Difference Time-Domain (FDTD) method.The hybrid cavity exhibits high-quality WGMs with a highQ factor of up to 800. Moreover, the resonant wavelengthcan be electronically controlled through modulation ofgraphene's Fermi level, enabling coverage of the entirefree spectral range at infrared frequencies. By depositinga thin layer of bio-molecular material (e.g., CBP) onto thesurface of our hybrid cavity, we are able to accurately readout the absorption spectrum at multiple spectral points,thereby achieving broadband fingerprint retrieval for thetargeted bio-molecule. Our results pave the way for highlysensitive, chip integrated, miniaturized, and electricallymodulated infrared spectroscopy biosensing.