光温双控太赫兹波调制特性研究

摘要

基于多频带金属开口谐振环结构,利用GaAs材料的光敏特性和VO2薄膜的热致相变特性,设计了一种既能实现光控又能实现温控的太赫兹(Terahenz,THz)波调制器,研究了光强和薄膜温度对THz波调制特性的影响.结果表明,随着光强的增加,谐振频率均出现蓝移且谐振强度减小,当光强达到0.2μJ·cm-2时,第二个谐振点(0.52 THz)蓝移了0.14 THz,透射幅度增加达50％;随着VO2温度增加至相变温度以上,THz波透射幅度急剧减小,在0.63 THz处透射幅度减小达45.5％;当光强和温度同时控制时,随着光强和温度的增加,谐振点频率蓝移且谐振点处的THz波透射幅度增加,但在温度超过相变温度后,则温度控制起主导作用.设计的THz波调制器能通过光控和温控实现对THz波的明显调制效果,可为实现多功能的THz波功能器件的设计及应用提供参考.%Based on the multi-bands metallic split-ring resonator,the terahertz (THz) wave modulator which has been designed and modulated by optical and thermal control with the application of the photosensitive properties of GaAs material and the thermal induced phase transition properties of VO2 films.In addition,the influence of pump laser fluence and film temperature on the THz wave modulation characteristics has also been studied.The results show that multi-resonances frequency presents blue shift and the resonance strength decreases with the increasing of the pump laser fluence.Moreover,the frequency in the second resonance point (0.52 THz) is blue shifted by 0.14 THz and transmission amplitude increases at 50％ for the pump laser fluence of 0.2 μJ · cm-2.Furthermore,the transmission amplitude of the THz wave decreases sharply when the temperature is over the VO2 phase transition temperature,and the transmission amplitude at the peak of the transmission spectrum of 0.63 THz decreases 45.5％.Finally,for the case of controlling by pump laser and temperature simultaneously,the resonance frequency also blue shifts and the transmission amplitude of the THz wave at the resonance point increases with the increasing of the pump laser fluence and film temperature.However,the film temperature plays a main role when it is over the VO2 phase transition temperature.The THz wave can be modulated obviously based on the designed THz wave modulator by controlling the light fluence and the film temperature,which can provide useful reference for the design and application of multi-functional THz wave function devices.