| Graphene is an emerging material with excellent electrical and optical properties and is widely used in the mid-infrared to terahertz regions.Graphene has also been widely used in various plasma waveguides in recent years.It has the characteristics of low relative loss,strong electric field limitation and simple regulation of chemical potential.Waveguides are the channels through which light travels in optical devices.The use of terahertz waveguides enables a variety of applications in the field of integrated optics and communication.In order to effectively control terahertz signals on photonic chips,it is necessary to design a waveguide with high quality factor（FOM）and low loss.Hyperbolic metamaterials are interesting because of their unique optical properties.In this paper,a new optical waveguide with high quality is designed based on hyperbolic material h BN crystal by theoretical calculation and COMSOL software simulation.The different modes,adaptive frequency and propagation quality performance of the waveguide are analyzed and calculated.The main research contents are as follows:1.Terahertz waveguides have a wide range of applications,including integrated optics and communications.To facilitate the control of terahertz signals on photonic chips,in this paper we propose a terahertz waveguide consisting of a dielectric ridge and a graphene layer sandwiched between two hexagonal boron nitride（h BN）ridges on a gold layer.Numerical simulation shows that the proposed waveguide has two types of guiding modes in the second coband of h BN（1360.02cm-1<ω<1609.98cm-1）.These modes are formed by coupling two h BN ridges of hyperbolic phonon polaron（HPhP）in intermediate dielectric ribs,which are then modulated by graphene layers.2.The changes of four waveguide transmission parameters（including effective length,quality factor,device length and propagation loss of the boot mode）with varying operating frequency and grid voltage are calculated.The modal characteristics were analyzed by changing geometric parameters and permittivity.Simulation results show that high FOM of 4.0×107 is achieved by optimizing dimension parameters of waveguide.The proposed waveguide provides a promising method for the design of tunable terahertz waveguides on photonic chips.The proposed method can be extended to other hyperbolic and two-dimensional materials,such as MnO3,organosilicon and germanene. |
