Theoretical Investigation On Multifunctional Computing Devices Based On Surface Plasmon Polaritons

In recent years,with the rapid development of various communication technologies,the information sharing of the whole society is more and more extensive.A tremendous amount of information in the network or each terminal unit also needs to be processed when people enjoy the convenience of exchanging information,which puts higher demands for the information processing ability of integrated circuit(microchip).The information processing ability of integrated circuit is largely determined by its integration.However,the traditional electronic integrated circuit is difficult to break through its inherent physical limits and technical bottlenecks because its integration has reached the nanometer level.And the electronic integrated circuit also has many shortcomings that can't be ignored,such as slow transmission speed,poor anti-interference ability,narrow bandwidth,high power consumption.Therefore,it is difficult to meet the demand of further improvement of integration of electronic integrated circuit.Optical integrated circuit has the advantages of ultrahigh speed,low power consumption,ultrawide-band information processing,which is the research hotspot of scholars all over the world in recent years.And it is expected to replace electronic integrated circuit.Micro-nano-scale silicon-based optical integrated circuit has achieved great research achievements that can be manufactured and applied.However,the size of optical devices based on silicon is limited to the half wavelength range of light due to the diffraction of light.It can't meet the demand of further improved integration.Surface plasmon polaritons,an electromagnetic wave that propagates along the metal surface,is formed by the resonance between the free electrons on the metal surface and the incident light.It exhibites a highly localized and surfaceenhanced property.Based on this characteristic,the breaking of the classical diffraction limit and the manipulate of light in the sub-wavelength range can be realized.It can meet the demand of further improved integration of the optical integrated circuit.All the information will be converted into data stream and processed by integrated circuit,and the basic operation is the Binary operation.So the computing device which realizes the function of logic operation is the core component of processing information integrated circuit.The structure based on surface plasmon polaritons can increase the integration of photonic integrated circuits.Therefore,the research of computing devices based on surface plasmon polaritons plays an important role in improving the information processing ability of optical integrated circuit.This paper designs a multiple logic operations device and a multifunctional computing device based on SPPs.The main content of the research of the paper are as follows:1.The classical free electron gas model of metals is introduced to describe the properties of the metal in this paper.According to Maxwell's equations,the dispersion relation of surface plasmon polaritons is obtained.The special properties of surface plasmon polaritons such as breaking through the diffraction limit of light and subwavelength constraint are theoretically proved.This paper also gives a brief introduction of the excitation methods of surface plasmon polaritons.2.A novel multiple logic functions device based on surface plasmon polaritons is proposed,which consists of two semi-circle cavities and a rectangular waveguide.The transmission spectrum of the device has more steep transmission peaks.The resonant wavelength shifts when the refractive index of the semi-circle cavities changes.Based on the characteristic,six logic operations can be achieved at the same time in the structure by monitoring the different wavelengths.3.A novel multifunctional computing device based on surface plasmon polaritons is proposed.It consists of a pair of vertical waveguides and a pair of transversal waveguides.Two groups of waveguides intersect to form a ring rectangular cavity.By changing the initial phase of the input light,the interference effect in the ring rectangular cavity can be controlled,so as to control the transmission ratio of the output port.Based on this characteristic,the device can be used as a half adder or a half subtractor.The proposed two logic operation devices based on surface plasmon polaritons play an important role in improving the integration of photonic integrated circuit.