Fabrication Of Terahertz Metamaterial By Laser Printing And Resonator Research

Metamaterials is a new kind of artificially engineered electromagneticmaterials constructed by the sub-wavelength metallic unit cells. Different fromvarious natural materials, metamaterials can achieve the desired electromagneticcharacteristics by adjusting structure of the unit cells, and can be applied to thenegative refraction index, electromagnetic cloaks, electromagnetically inducedtransparency or other fields. With the developing of THz radiation generation anddetection technology in the decade, research of terahertz metamaterials gainedfurther development. The analogue of EIT effect in THz metamaterials was going tobe a hot pot gradually, the resonators have various applications on fields of slow light,optic storage, chemical and biological sensing.In this paper, we designed some resonators which can realize analogue of EITeffect. We respectively simulated and measured the transmission characterization ofthe resonators with CST and THz-TDS. Currently, the main fabrication method ofterahertz metamaterial is the conversation lithography. There is some internationalreport that some emerging technologies such as inkjet, laser printing, laser-inducedand chemical non-electrolytic plating were also using for metamaterials fabrication.We researched and constructed the laser printing system used for THz devicefabrication. The main works of the dissertation are listed as followed.(1) We proposed the way to fabricate terahertz devices based metamaterials onthe PET films by the laser printing process, which revealed the advantages of lowcost, simple process, and flexible to fabrication arbitrary shape of metal microstructures. The main work included the preparation of laser printing system fordevices, the technological process research of fabrication and the sample preparation.Recently, we could fabrication metal structures with size of micrometers regimeusing our laser printing system, the laser printing system was a hopeful process tofabricate various terahertz device.(2)A terahertz EIT resonator based on a combination of the two asymmetry halfrings was proposed, the transmission properties of the resonator was simulated andexperimental measured using CST and THz-TDS. The results showed that EIT effect can be achieved between0.1-0.6THz, because of anti-symmetric excitations form anarray of magnetic dipoles oscillating perpendicular to the plane of the metamaterialwhen the electric polarization perpendicular to the gap between the two half-ringresonators. When the electric polarization was parallel to the gaps, the EIT resonatorhad two resonance peaks between0.4-0.9THz, which due to a destructiveinterference excited by the interference between anti-parallel current pairs thatcompletely suppressed the scattering allowing the incident wave to be transmitted.Numerically simulated the transmission properties as parameters changed whenelectric polarization perpendicular and parallel the gaps, results indicate that changesin line width tremendously affect EIT transmission properties of the resonator, thegap and metal thickness varied weakly impacted the transmitter spectra of theresonator.(3) One kind of terahertz resonator consisting of split-ring resonator (SR) andcut wires (CW) and behaving like electromagnetically induced transparency (EIT)was studied theoretically and experimentally. The transmission characteristics of theresonators containing one or two gaps for the split ring are numerically simulated,including the impact of the relative position of the split ring on their resonant peaksand width. The resonant peaks of EIT spectrum of SR/CW resonators are foundaround0.7THz due to destructive interference between the LC resonance of thesplit-ring resonator and the dipole resonance of the cut wires. Both the amplitude andQ-factor of the EIT resonance are very sensitive to the position shift of the split ringfor the SR/CW resonator with one gap, and insensitive for the two gaps. Finally, theSR/CW resonators were fabricated on polyimide substrate using laser-induced andchemical non-electrolytic plating with copper, the transmission properties of whichcharacterized by THz-TDS are in good agreement with simulations.