Point-of-care sensors are pivotal for early disease diagnosis,significantly advancing global health.Surface plasmons,the collective oscillations of free electrons under electromagnetic excitation,have been widely stud...Point-of-care sensors are pivotal for early disease diagnosis,significantly advancing global health.Surface plasmons,the collective oscillations of free electrons under electromagnetic excitation,have been widely studied for biosensing due to their electromagnetic field enhancements at sub-wavelength scales.We introduce a plasmonic biosensor on a compact photonic integrated circuit(PIC)enhanced by exceptional points(EPs).EPs,singularities in non-Hermitian optical systems,provide extreme sensitivity to external perturbations.They emerge when two or more complex resonating modes merge into a single degenerate mode.We demonstrate an EP in a single coupled nanoantenna particle positioned in a uniquely designed silicon nitride slot-waveguide,which we call a junction-waveguide.By laterally shifting two optically coupled gold nanobars of different lengths,we achieve a single particle EP.The junction-waveguide enables efficient coupling of the plasmonic nanoantenna to the waveguide mode.The system integrates a four-port Mach-Zehnder interferometer(MZI),allowing for simultaneous measurements of the amplitude and phase of EP,facilitating highly accurate real-time eigenvalue extraction.For biosensing,we encapsulated the detection zone with a microchannel,enabling low-volume and simple sample handling.Our single particle integrated EP sensor demonstrates superior sensitivity compared to the corresponding linear diabolic point(DP)system under both local and bulk sensing schemes,even at large perturbations.Our studies revealed that the integrated EP sensor can detect a single molecule captured by the nanobars with the average size ranging from 10 to 100 nm.The proposed EP biosensor,with its extreme sensitivity,compact form,and real-time phase sensing capabilities,provides an approach for detecting and quantifying various biomarkers such as proteins and nucleic acids,offering a unique platform for early disease diagnosis.展开更多
基金Army Research Office(W911NF2310027)NIH(S10OD034382)。
文摘Point-of-care sensors are pivotal for early disease diagnosis,significantly advancing global health.Surface plasmons,the collective oscillations of free electrons under electromagnetic excitation,have been widely studied for biosensing due to their electromagnetic field enhancements at sub-wavelength scales.We introduce a plasmonic biosensor on a compact photonic integrated circuit(PIC)enhanced by exceptional points(EPs).EPs,singularities in non-Hermitian optical systems,provide extreme sensitivity to external perturbations.They emerge when two or more complex resonating modes merge into a single degenerate mode.We demonstrate an EP in a single coupled nanoantenna particle positioned in a uniquely designed silicon nitride slot-waveguide,which we call a junction-waveguide.By laterally shifting two optically coupled gold nanobars of different lengths,we achieve a single particle EP.The junction-waveguide enables efficient coupling of the plasmonic nanoantenna to the waveguide mode.The system integrates a four-port Mach-Zehnder interferometer(MZI),allowing for simultaneous measurements of the amplitude and phase of EP,facilitating highly accurate real-time eigenvalue extraction.For biosensing,we encapsulated the detection zone with a microchannel,enabling low-volume and simple sample handling.Our single particle integrated EP sensor demonstrates superior sensitivity compared to the corresponding linear diabolic point(DP)system under both local and bulk sensing schemes,even at large perturbations.Our studies revealed that the integrated EP sensor can detect a single molecule captured by the nanobars with the average size ranging from 10 to 100 nm.The proposed EP biosensor,with its extreme sensitivity,compact form,and real-time phase sensing capabilities,provides an approach for detecting and quantifying various biomarkers such as proteins and nucleic acids,offering a unique platform for early disease diagnosis.
