Study On All-optical Logic Gate Based On Surface Plasmon Polaritons

Surface Plasmon Polaritons(SPPs)are surface electromagnetic waves formed by the interaction of photons and electrons on the metal-medium surface.SPPs are propagating along a metal-dielectric interface with an exponentially decaying field in both sides.Surface plasmons have unique optical properties that can break through traditional diffraction limits,enabling optical components to be smaller in size and facilitating largescale integration of photonic devices.Surface plasmon has broad application prospects in various technical fields,including surface plasmon waveguides,biosensors,nano-optical antennas,and optical storage.As a key component of all-optical calculation and processing,all-optical logic gates play an important role in overcoming the basic performance limitations of electronic devices.In the thesis the basic theory of surface plasmon is firstly introduced,then the basic properties of surface plasmon propagation in metal-insulator-metal(MIM)waveguides are analyzed.Finally,the all-optical logic gate devices are designed and analyzed based on the MIM waveguide structure.The main contents are as follows:1)Based on the nano-cavity of MIM waveguide,the basic properties of surface plasmons propagating in nano-cavity are analyzed.The distribution equation of the magnetic field resonantly propagating in the cavity is solved.Then applying the distribution equation,the logic gate structure of different functions is designed by setting certain parameters and changing its input and output terminals respectively.The functions of some general logic gates are studied and analyzed by Finite Difference Time Domain(FDTD)method,and the ones of some specific logic gates are verified by FDTD Solutions software.In the simulation results the magnetic field strength distribution map and the transmission spectrum are analyzed.2)The properties of transverse spin of the structured optical field are analyzed,and the circularly polarized dipole generated by optical fields with transverse spins can excite the unidirectional propagation of surface plasmons in the waveguide.The logic gate structure based on the transverse spin of the light field is studied.The metal nanospheres were used as nano-antennas to excite the surface plasmons into the MIM waveguide.The XNOR and XOR logic gate infrastructure models were designed by adjusting the shape and parameters of the MIM waveguides.The functions of these logic gates are verified and analyzed by simulation of FDTD.