Study On Manipulation Techniques And Devices For Terahertz Wave

As the development of the terahertz (THz) science,the fascinating application potentials in spectrum analysis,imaging,security,and communication are found more and more close to the human being's life and THz science has been receiving more and more attention from kinds of fields . Since the research on THz science is more lagging than other frequency regions,such like microwave and visible range,effective manipulation methods on THz waves are extremely limited and that is also the reason why so many people pay so hard word on it. In this thesis,four parts are included as followed about THz manipulation to the amplitude as well as the spectra.First , the semiconductor-metal phase transition properties of vanadium oxide(VOx),especially the photo-induced phase transition,are studied by using terahertz time domain spectroscopy (THz-TDS). The optical response of silicon based VOx film under different illuminating way,i.e. CW laser with various wavelengths and femtosecond laser pulses.Second,the filtering performances of hybrid surface plasmon polarition structures are examined by both numerical simulations and experimental measurements. The geometrical dependence of transmission frequency shift is analyzed by using phenomenological molecule model. The coupling between different-typed SPPs modes are studied by theoretical analysis and experiment results and the coupling coefficient is calculated.Third,combined the optical modulation feature of silicon-based VOx films and the filtering effect of SPP structures,composite structures like VOx film on metal hole array and VOx film on metal patch array were designed and so was the microstructured VOx film. The experimental measurements show obvious both filtering and modulating function in such devices, and optical frequency tunability is realized .Last,by using its modulation effect to THz waves,the silicon-based VOx film was employed as an optically controlled THz chopper,a necessary element of THz-TDS,and THz pulses are succeded to be measured instead of traditional mechanical motor chopper. The origin of the difference between THz waveform measurements based on such optical chopper and normal mechanical chopper is analyzed.