Theoretical Investigation On Logic And Slow Light Devices Based On Surface Plasmon Polaritons

With the development of modern information technology,traditional electrical components have been unable to meet the contemporary demands for high integration and high speed of devices.Compared with electronic devices,photonic devices have natural advantages in terms of transmission bandwidth.Therefore,optical devices that fabricated using optical fiber have been extensively researched.However,the mismatch in size between traditional photonic devices and electronic devices makes optoelectronic integrated devices inferior in terms of size and power consumption.In order to further improve the integration of photonic devices,surface plasmon polaritons(SPPs)have gradually attracted attention.SPPs are electromagnetic waves that are formed by the coupling of the incident light field and free electrons on the metal surface.They are bound to the surface of metal-dielectric and propagate along the surface of metal.Because SPPs have the characteristics of surface enhancement and high localization,and have the advantage of breaking the diffraction limit,the propagation and manipulation of optical signals can be realized in metal structures with subwavelength size.At present,the theoretical research of SPPs is gradually completed,and great progress has been made in many fields including integrated waveguide and new light source based on SPPs.In order to promote the development of optoelectronic integration,two novel devices,which are logic device and slow light device,are designed in this dissertation.The main research contents of this dissertation are as follows:1.The research progress,basic properties,and applications in the optical devices based on SPPs are introduced in detail.The application and research status in the logic devices and slow light devices based on SPPs are emphatically discussed.In addition,the main work and significance of further research are summarized.2.The theoretical analysis model and numerical simulation method involved in this dissertation are explored.The theoretical analysis includes: the Drude model for solving the dielectric constant of metal materials,metal-insulator-metal(MIM)waveguide theory that can characterize the propagation characteristics of SPPs in MIM waveguide structures,and coupled mode theory for analyzing the transmission characteristics of the nanocavity coupled with waveguide.The numerical simulation method to verify the theoretical analysis is the finite-difference time-domain(FDTD)method.3.A multifunctional logic device with novel manipulation method is proposed,which mainly consists of a hexagonal cavity and two rectangular cavities in which two sliders are embedded.Different input states are characterized by different positions of the slider.The coupled mode theory shows that the slider in different positions will affect the transmission spectrum.By manipulating the slider,three logic operations can be realized in the designed structure simultaneously,and the numerical verification is performed by the FDTD method.In addition,the effects of structural parameters on device performance are explored.The proposed structure with novel operation method can provide new ideas for designing other photonic integration devices and has extensive application prospect.4.A slow light device with multiple plasmon-induced transparency(PIT)phenomena is proposed.The device mainly consists of two tooth cavities coupled with stub resonators,respectively.The coupled mode theory shows that three PIT peaks are generated by two different physical pathways.The first physical pathway is the direct coupling between the radiative resonator and subradiant resonator,and the second physical pathway is the indirect coupling between two detuned resonant cavities.According to the formation reasons,we found that the two PIT phenomena generated by the first physical pathway can be manipulated separately.Therefore,the slow light characteristics of two PIT windows generated by the first physical pathway are investigated using the FDTD method.In addition,by adjusting the structural parameters,the transmission,group index,and operating wavelength of the two slow light regions can be manipupulated.The slow light phenomenon at multiple wavelengths can be realized in proposed device simultaneously,which further improves the integration of the device and has important application value.