The Research Of Terahertz Tunable Devices Based On MEMS

The terahertz(THz)wave,which lies between the millimeter wave and infrared in the spectrum,has many appealing and unique properties.As THz technology plays a significant role in modern systems,it has been widely studied all over the world.Considering the size and cost of the systems,the problems of miniaturization and multi-function are crucial for application systems in terahertz.Hence,this paper is dedicated to designing tunable and high-performance passive devices for its effectiveness in solving such problems.With the development of MEMS(microelectro-mechanical systems)technology,many kinds of micro actuators merge,which provides new ideas for designing terahertz tunable filters,terahertz waveguide switch,and terahertz tunable wave absorber.The contents of this paper are as follows:(1)The paper introduces a variety of micro actuators including the driving way and working principles,especially the thermal micro actuators using MEMS technology and PolyMUMPs processing.Based on the theory,Bimorph thermal micro actuators and U-shaped micro actuators are designed by simulation through software ANSYS.Several kinds of Bimorph thermal micro actuators are processed after the feasibility analysis.The measured results meet the expectations,which provides a theoretical basis for tunable devices.(2)The paper introduces the prototype of the terahertz filter,and proposes four kinds of tunable terahertz filter with the combination of micro actuators.One terahertz filter is processed which uses Bimorph micro actuators to generate perpendicular displacement to the base.The micro actuators can change the size of resonance cavity and tune the center frequency.The measured results meet the requirements.The processing and assembling methods are discussed,and the detailed tolerance analysis is given.A large amount of engineering experience has been accumulated.(3)Temperature controlled terahertz waveguide switch can effectively use MEMS thermal micro actuators' characteristic that the metal diaphragm can rotate when the temperature rises.It can conduct and block electromagnetic wave.A waveguide switch is designed,processed,and measured.The proposed waveguide switch can conduct and block transmitting microwave,thus solves the connection and integration problems of terahertz waveguide systems.(4)Based on the theory of electromagnetic band gap,the absorbing characteristic of metamaterials,and the displacement of micro actuators,three different kinds of tunable wave absorber in terahertz spectrum are proposed.These tunable wave absorbers can realize the frequency selectivity function in space for terahertz.