Research Of The Multifunctional Logic Device Based On Plasmon-Induced Transparency Effect

In the era of high-speed development of modern intelligent communication network,traditional electrical communication has been unable to meet the contemporary pursuit of fast speed,large capacity,low loss,miniaturization and other highly performance communication systems,electrical communication is replaced by optical communication gradually.With the popularization of optical communication technology,the corresponding optical communication product which is the optical device also emerges at the historic moment.Optical device,as one of the key components of the optical communication system,has been developed extensively since the early twentieth century.At first,semiconductor materials were used to make optical devices.However,with the deepening of research and the pursuit of highly performance,such as miniaturization and integration,people gradually focus on a substance called surface plasmon polaritons(SPPs).SPPs is a kind of electromagnetic wave that can overcome the diffraction limit and operate optically at sub-wavelength scales.Appearance of the SPPs provides a greater possibility to solve the problem of photonic device integration.With the development of the SPPs research,a special effect has attracted scholars' attention.It is similar to the electromagnetically induced transparency(EIT),which is named plasmon-induced transparency(PIT).Compared with the EIT effect,the PIT effect can get rid of strict realization conditions.It is able to be realized in room temperature,and the integration of devices can be improved furtherly.Besides,PIT effect also has the characteristics of narrow bandwidth,fast response speed and low loss.These characteristics make PIT effect have wider application prospects in the optical device.Optical logic device,as the core device of optical switching and optical computing,plays an important role in the new generation of optical networks.Therefore,based on the PIT effect,a new kind of multifunctional logic device is proposed in this paper,which is realized by using angle control method.The research contents of this paper are as follows:Firstly,the development history of the optical logic device is introduced in detail.Then,the basic properties,development status,physical phenomena and applications in the optical logic device of SPPs are discussed.The main work and research significance are summarized,which lay the groundwork for the follow-up of the paper.Secondly,the theoretical analysis model and numerical simulation method used in this paper are explored.The theoretical analysis can be divided into two aspects.First of all,according to Drude model and Maxwell equations,the dielectric constant of metal and the dispersion characteristics of SPPs are obtained.Then,the transmission characteristics of SPPs in different structures are analyzed by time domain coupled mode theory.The numerical simulation method is based on the finite-difference time-domain(FDTD)method to verify the theoretical results.Then,based on theoretical researches,a new plasmonic structure is designed in this paper,which can realize the manipulation of PIT effect.The structure consists of a metalinsulator-metal(MIM)waveguide and a hexagonal resonator embedded with a rotatable ellipse.By controlling the angle of metal ellipse,the PIT effect can be adjusted.In addition,the influence of the parameters such as the side length of the hexagonal resonator,the radius of the elliptical long axis and the short axis,the coupling distance and the refractive index of the medium inside the resonator on the transmission characteristics of the PIT effect is also investigated.The structure is controllable and has many applications,which provides an important idea for the design of optical logic gates.Finally,a multifunctional optical logic device based on PIT effect is designed.The device consists of two hexagonal resonators embedded with metal ellipses and two MIM parallel waveguides.Two metal ellipses are used as input signal controllers respectively.By changing the rotation angle of the ellipse,the input state can be adjusted.Finally,the output results under different input states can be obtained by analyzing the transmission efficiency of different output ports.Therefore,we can realize many kinds of logic functions in the device.The realization of this function has important application prospects in the design of optical integrated circuit.