Research Of Subwavelength Transmission And Phase Modulation Technology Based On Surface Plasmon Polartions

The development of silicon-based optoelectronics provides a new direction for solving the problems of quantum effects currently faced by integrated circuits.However,due to the existence of the diffraction limit,the size of traditional optoelectronic devices is difficult to shrink to within the same order of magnitude as microelectronic devices,which severely restricts the improvement of the integration of optoelectronic devices.Surface plasmon polariton is evanescent electromagnetic waves that propagates along the conductor-medium interface.It can break the diffraction limit and confine the light wave field tightly on the metal surface.It is an effective means to realize sub-wavelength confinement optoelectronic devices.Graphene is a new low-dimensional material with many excellent properties.Compared with metal surface plasmons polariton,graphene surface plasmons polariton has low loss and tunable characteristics.For optoelectronic chips,waveguides and modulators are the core components,which play an important role in optical interconnection and signal modulation.Facing the need to further improve the integration of optoelectronic chips and the miniaturization of photonic devices,this paper proposes two types of surface plasmon-based optoelectronic devices with deep subwavelength limitation: hybrid plasma waveguide and graphene-based surface plasmon Exciton’s phase modulator.The main works of this paper are:(1)Based on the significance of silicon-based photonics,the research significance of hybrid waveguides and graphene modulators based on surface plasmons polariton was demonstrated,and their current development status was summarized.(2)Based on Maxwell’s equations and electromagnetic field boundary conditions,the surface plasmon polariton(SPP)dispersion relationship of the medium-metal interface in a semiinfinite space is derived.The law of the optical frequency response of the metal with the wavelength of the incident light is analyzed.(3)In order to solve the problem of low transmission length and weak localization of the optical field in the current hybrid waveguide,a new type of hybrid circular-triangular prism SPP waveguide structure is proposed.The influence of various structural parameters of the waveguide on its mode distribution and transmission properties is simulated by COMSOL software.Due to the unique round-triangular prism structure,the optical field in this waveguide is tightly confined to the silicon dioxide dielectric region.The results show that the transmission length can reach 500 um,the normalized mode area is less than 0.012,and it has a deep sub-wavelength limitation while maintaining a long transmission distance.(4)Based on the Kubo formula,the photoconductivity tunability of graphene is calculated and analyzed.The plasmon dispersion equation on the graphene surface is derived.Based on this,a phase modulator based on graphene surface plasmons is proposed.The mechanism of the modulator using the graphene Fermi level and photoconductivity tunable characteristics to achieve phase modulation is calculated in details.Meanwhile,COMSOL software is used to simulate the model.The results show that under low driving voltage conditions,the modulator can achieve a wide range of phase change of 30°.