Regulating Research Of Terahertz Waves For Tini Memory Alloy Thin Films

TiNi shape memory alloy thin films will undergo phase transition from B2 structure of the parent phase to B19 'structure of the martensite phase around the phase transition temperature,with dielectric properties and shape of the material can be changed rapidly.So TiNi alloys can be prepared into thin films and combined with the design of metamaterials to achieve double modulation of material properties and structure under the action of temperature field,then the terahertz waves can be regulated dynamically.Terahertz functional devices made by TiNi alloy thin film metamaterials have the advantages of fast regulation speed and wide modulation range.It provides a new idea for the development of terahertz functional devices made by TiNi alloy thin film metamaterials.First of all,we design a structure of TiNi film metamaterials,different the temperature field can change the conductivity,surface roughness and structure of TiNi thin film metamaterials,and get the corresponding transmission spectrum.Then we analyze the mechanism of TiNi metamaterials respond to terahertz waves by coupling resonance principle.In addition,we study the effects of metamaterials conductivity,surface roughness and deformation on terahertz waves in the process of TiNi thin films phase transition.The results show that the terahertz resonant frequency respectively produces a modulation of 0.14 THz and 0.46 THz because of the change of TiNi metamaterials' conductivity and surface roughness.And because the large deformation of TiNi films,the terahertz resonant frequency produces a modulation of 0.5THz.So TiNi metamaterials have good modulation effect on terahertz waves.Based on the above theory,we discuss the application of TiNi metamaterials in modulator and filter.For the terahertz modulator,phase transition of TiNi metamaterials achieves the modulation effect of 0.3THz and The modulation effect of 0.46 THz was achieved by structural deformation.The dual modulation of TiNi thin film metamaterials achieves the effect of 0.85 THz.For the terahertz filter,we choose TiNi thin film metamaterials that contain the dielectric layer,which can get the wide band stop filter.The phase transition and structural transition of TiNi metamaterials achieve the modulation effect of 0.07 THz and 0.15 THz,and the dual modulation of TiNi thin film metamaterials achieves the effect of 0.27 THz.The result what we want is achieved by the double modulation of material characteristics and structures.The study show that TiNi thin film metamaterials have great potential in terahertz functional devices.