Research On Integrated Terahertz Waveguide Based On STIRAP Of Quantum Control Technology

Surface Plasmon Polaritons(SPPs)have attracted increasingly attentions because of their unique subwavelength characteristic and strong field confinement ability.They have been widely used in integrated circuits biosensors and super-resolution imaging.At the same time with the continuous exploration of terahertz it is urgent that the research of terahertz functional devices should be investigated.In this paper we study the terahertz surface plasmon polaritons waveguide based on the quantum control method--Stimulated Raman Adiabatic Passage(STIRAP).First of all according to the principle of STIRAP it is known that its principle is to use two overlapping pulsed lasers(pump pulse and Stokes pulse)to realize the layout transfer in atoms or molecules.In such a system energy can be completely transferred from the initial state to the final state without staying in the intermediate state.This is because the Stokes pulse must works precede the pump pulse.Only such a counter-intuitive sequence can enable our waveguide to completely transfer energy from the input to the output during the transmission process.It can be seen that the design of two Gaussian-shaped counter-intuitive pulse sequences similar to pump pulses and Stokes pulses is the key to transfer energy completely in the waveguide system.As to the design of the waveguide it can be achieved by rewriting the coupling coefficient curve between waveguides.In this article we first simulated the electric field transmission of parallel SPPs waveguides with different gap distances.According to the electric field diagram we can get the relationship of the coupling coefficient under different gap distances the function formula also can be defined and then rewrite the function curve into a counter-intuitive pulse sequence similar to two overlapping Gaussian shapes in STIRAP.Until now we have completed the first step in the complete energy transfer process in the waveguide system.Secondly Once the pulse curve of the Gaussian shape is determined the specific parameters of the waveguide structure are also uniquely determined.For the three-level system in quantum control the proposed structure model of the terahertz surface plasmon polaritons waveguide is presented which is a new type of terahertz integrated device with asymmetrical curved structure.It consists of two asymmetrical curved waveguides and a straight waveguide.Finally the propagation characteristics of terahertz surface plasmon polaritons waveguide are verified by simulation results.We simulate and configure our proposed waveguide in the simulation software CST and MATLAB the simulation results show that the waveguide model proposed in this paper can support the transmission of SPPs in the terahertz band on the surface of the structure and the waveguide designed by the quantum control method can achieve stable transmission over a wide band.In the frequency band of0.5THz-0.8THz the waveguide structure proposed in this paper always maintains a transmission efficiency of more than 70%;At the same time the robustness of the device was verified and the results showed that when the geometric parameters of the device(,(9 )were changed in a wide range the transmission efficiency of the device stabilizes at a level above 80% indicating that the device possesses perfect robustness.In addition this article also investigates the application of quantum control in other systems.It is mainly divided into three parts: 1.A proposal design for robust and broadband microwave SPPs waveguide coupler via STIRAP;2.Complete and robust light transfer in three-waveguide coupler by shortcut to adiabaticity;3.Long distance adiabatic wireless energy transfer via multiple coils coupling.In the three systems mentioned above it is confirmed that the quantum control method can help maintain the robustness of the system while maintaining an efficient and stable transmission state.