Research On Terahertz Wave Modulator Based On Graphene

The communication devices of terahertz wave which the basic problems of sources and detectors solved has become the focus of research.Modulator which is the core component of communication system are widely used in a variety of systems,such as biomedical and sensing systems,etc.Therefore,the study of high-performance modulator has become one of the hot spots in the field of terahertz.Graphene is an ideal material for designing high-performance terahertz wave modulator because of its excellent electrical properties.In this paper,the equivalent circuit method is used to study the graphene-based terahertz wave modulator.The main contents are as follows:Firstly,this paper introduces the basic properties of graphene,and studies the equivalent circuit model of the modulator based on graphene.Those works lay a theoretical foundation for the analysis and design of high-performance terahertz wave graphene modulator.Secondly,the transmission parameters of graphene-based modulators are analyzed by the three-dimensional simulation software on the basis of the above theory.The modulating speed and working bandwidth of the modulator are calculated theoretically by the equivalent circuit method.The transmission modulator has the characteristics of high modulation speed(152KHz),wide bandwidth(264KHz)and low transmission loss(0.3dB).The reflective modulator has the characteristics of high modulation depth(96%),wide bandwidth(72KHz)and low bias voltage(4V).The designed modulator is manufactured and tested in the laboratory.The results show a modulation depth of 61%.A complete analysis and test model are obtained by comparing experimental test data with simulation results.Finally,a high-performance modulator based on frequency selective surface and graphene is analyzed.To obtain the final optimization model,the geometric parameters such as the number of layers of graphene and the position of frequency-selected surface are analyzed by the three-dimensional simulation software.The modulation depth is more than 90% in the working bandwidth which from 0.23 THz to 0.6THz.The final results show that the software simulation and theoretical calculation which calculated by the equivalent circuit method are approximately equal,which provides an effective analysis method for the analysis and calculation the modulator.