Research Of Terahertz Functional Devices Based On Metal Surface Plasmon Polaritons

The progress on terahertz (THz) sources and detectors brings the speedy developing of research on applicction of THz technology. The reaserach of functional devices is of great interest in recent years.The specific properties of metal surface plasmon polaritons (SPP) enables THz wave to propagate through sub-wavelength arrays or propagate along periodic corrugated metal surface. According to the different properties on plasmon oscillation, surface plasma (SP) can be termed as propagating surface plasmon (PSP) and localized surface plasmon (LSP). Based on the specific characteristics of these two kinds of SP, several functional devices were proposed and studied in this thesis.(1) A narrow-band terahertz filter based on metal-dielectric-metal (MDM) structure with circular loop array patterned on metallic films was proposed. The transmission properties in terahertz range of the structure were experimentally and theoretically analyzed. The structure’s transmission spectrum has two narrow-bands. The narrow-band in lower frequency range was dominated by transmission mode due to LSP and the one in higher frequency range was dominated by PSP mode and guided mode. Both narrow-bands have high Q-factor. By designing asymmetry periodic constant in orthogonal directions, the narrow-band domained by PSP exhibit potentials as narrow-band polarizer. Furthermore, the transmittance of polarizer can be promoted to 100% by laterally shifting the metallic arrays.(2) A THz modulator was proposed based on a multi-layers structure. By adjusting the permittivity of dielectric layer outside of MDM, the resonance frequency of propagating plasmon polaritons can be modulated. The mechanism of modulator was studied. Experiments were operated and verified the feasibility of that design.(3) A terahertz band-stop filter was proposed based on the transmission properties of parallel metal plates with corrugated grating grooves. The influence of geometry parameters to filters’s transmision properties were theoretically and experimentally studied. The bandwidth of the stop-band can be adjusted by changing the width between two plates. The filter exhibits well transmittion properties in lower frequency range which lay fundation to further appliction designing.(4) A cross structure consisted of parallel corrugated metal plates and metal blocks engraved with air loop was proposed. The transmission properties of cross structure were simulated and analyzed. The resonance transition between propagation surface plasmon and localized surface plasmon plays key role in the transmission process of cross structure. The structure exhibits potential application as a beam splitter with a broad operating frequency range and can split waves with its optical properties unchanged.