Research On The Design And Detection Mechanism Of Micro-nano Optical Sensor Based On Optical Constraint Characteristics

The optical confinement characteristics of micro-nano structures at subwavelength scales can effectively enhance the interaction between light and matter,bringing new opportunities for development in the field of sensing,and attracting widespread attention from researchers.Despite the rapid development of micro-nano optical sensors,there are still several crucial issues that need to be addressed.For instance,due to the limitations of material selection and structural design,micro-nano optical refractive index（RI）sensors suffer from low sensitivity,high transmission loss,and poor resistance to disturbances.Additionally,the sensing mechanism based on the change of bulk RI is incapable of achieving high-sensitivity detection of a small number of nanoparticles,thereby restricting the application range of micro-nano optical sensors.To address these issues,this paper proposes the design of various novel sensors and the exploration of detection mechanisms,aiming to enhance the detection performance and expand the application scope of sensors.The main research work of this paper is summarized as follows:（1）Based on the sensitivity of Kretschmann prism structure to changes in RI of analytes,three RI sensors were designed,which possess characteristics of high sensitivity,low full width at half maximum（FWHM）,and high detection accuracy without polarization restrictions.By adding structural materials to modify the propagation constant of incident light and increase the contact area with analytes,a surface plasmon resonance（SPR）RI sensor device based on Fe₂O₃ and antimonene was designed,achieving a sensitivity of 398°/RIU.To reduce the FWHM and improve the detection accuracy,a long-range surface exciton polariton（LRSEP）sensor based on Cytop-TDBC-graphene structure was designed,which increased the overlap integration between light and matter,achieving a sensitivity of 3243 RIU^-1.To avoid the influence of polarization on the sensor,a lossy mode resonance（LMR）sensor based on Cytop-ITO-TMDs structure was proposed,enabling polarization-independent sensing,with sensitivities increased to 6438 RIU^-1 and6695 RIU^-1 for TE and TM polarized light,respectively.（2）To reduce the transmission loss of micro/nano optical sensors,avoid the influence of impurities or defects generated during the processing on the forward transmission of light waves,and improve the anti-scattering ability of the structure,a RI sensor based on the topological photonic crystal structure is designed.By analyzing the topological invariants and the topological boundary states of the valley photonic crystal,waveguides and ring resonators with topologically protected properties were constructed.Simulation results demonstrate that this structure exhibits low loss,immunity to defects,and unidirectional transmission.（3）To eliminate the perturbation of environmental temperature variations on sensing detection,two kinds of optical sensors based on mode coupling were designed by selectively enhancing the interaction between light and matter in the nanostructure.By using the difference between the resonant wavelength of the excited guided-mode resonance and the one-dimensional topological photonic state,a dual-resonance optical sensor based on the coupling of guided-mode resonance and one-dimensional topological photonic crystal was designed and fabricated.The results demonstrate that the structure can realize the simultaneous detection of dual parameters,eliminating the cross-interference caused by temperature variations.To further reduce the complexity of the sensor,an optical sensor based on an asymmetric dimer structure was designed by introducing different planar perturbations in the metasurface.This design excites two resonance modes with different resonance characteristics,resulting in an ultra-high quality factor（Q-factor）and achieving high-sensitivity dual-parameter detection.（4）To address the issue that bulk RI sensors cannot achieve efficient detection of nanoparticles,and further expanding the application range of micro-nano optical sensors,a tetramer dielectric metasurface optical tweezer sensor was designed based on the optical force detection mechanism.By using the resonant characteristics of symmetric tetramer dielectric metasurface,the diffraction limit was broken and a strong gradient force was provided for capturing nanoparticles with a radius of 10 nm,reducing the detection limit.Combined with the optical chirality enhancement of asymmetric tetramer dielectric metasurface,it shows unique chiral advantages.Simulation results showed that this structure can directly distinguish enantiomers,effectively separate chiral particles,improve the detection efficiency of optical biosensing,and provide an effective way to realize the capture,detection and separation of nanoparticles.