Design And Study Of MIM Waveguide Sensing Structure Based On Surface Plasmon Polaritons

Nowadays,communication technology using light as a carrier shows tremendous potential.Photonic device has faster speed,stronger stability and lower energy consumption compared with electron device.So,it is inevitable that the photonic devices become one of the research hotspot.Surface plasmon polaritons(SPPs)can be regarded as electromagnetic waves,which are generated by the interference of incident photos and free electrons on metal.Because SPPs can overcome the diffraction limit,it can control the photons in the nanoscale.There are many carrier of SPPs.And the metal-insulator-metal(MIM)waveguides are regarded as one of the comparatively preferred waveguide in the integrated optical device because of its excellent performances in easy fabrication and strong local enhancement.A host of researchers designed nanoscale structure based on MIM waveguide,which are applied in optical switches,beam splitters,filters and nanosensors.In our works,three structures with high sensing performance are proposed.Based on the phenomenon of Fano resonance,the sensing function is realized by detecting the shift of resonance dip.The transmission characteristics of the proposed structure are simulated by using finite element method.The detailed works are summarized as follow:1?A nanoscale optical structure,composed of a metal-insulator-metal waveguide with a stub and a horizontal number eight-shape cavity,is designed.The formation mechanism of Fano resonance in this structure is studied.Meanwhile,the influences of its geometric parameters on sensing performances are investigated in detail.Moreover,the influences of asymmetric resonator on different resonance dip are discussed.In the end,this structure can be applied in refractive index detection,and the best sensitivity of this nanosensor can reach1500 nm/RIU and its figure of merit(FOM)is 75.2?A nanostructure,composed of a metal-insulator-metal waveguide with a stub and a straight-through type ring cavity,is proposed.The formation mechanism of Fano resonance in this structure is discussed.The transmission characteristics of four derived structure are compared.The symmetric destruction of this design structure will excite a new resonant mode.Additionally,the effects of geometric parameters on sensing performances are investigated in detail.When this structure is applied in refractive index detection,the sensitivity can be achieved 1400 nm/RIU with a FOM of 100.3?A nanostructure,comprised metal-insulator-metal waveguide and a ring with a matchstick-shape cavity(RMSC),is designed.The influences of the position of matchstick-shape structure inside the ring and various structural parameters of RMSC on transmission characteristics are discussed.The matchstick-shape is the key structure to confine SPPs.In addition,considering the application of this structure,the maximum sensitivity achieve 2162 nm/RIU with a FOM of 52.73 when it is used for a refractive index sensor.Meanwhile,it can reach as high as 1.525 nm/? when it serves as the temperature sensor.When this structure serves as a biosensor for detecting glucose concentration,the sensitivity can achieve 0.45(nm·L)/g.In conclusion,three kinds of novel structure based on MIM waveguide coupling a resonator are proposed,which will contribute to the development of ultra-compact optical sensor.