by Jiaguang Han シンガポール大
The talk will focus on two topics: one is Terahertz plasmonic and metamaterial structure and the other one is materials characterization by Terahertz time-domain spectroscopy (THz-TDS).
Recently, extraordinary transmission in two-dimensional array of subwavelength holes has been widely investigated in a broad spectral range of electromagnetic waves. It has also demonstrated attractive interdisciplinary applications such as in photonics, optoelectronics, bioengineering, and nanofabrication. Generally, the enhanced, higher-than-unity transmission was attributed to the resonant excitation of surface plasmons (SPs) set up by the periodicity of the metallic hole array, where the light is coupled to SPs on the incidence surface of the array and reemit from the second surface afterwards. SPs are collective excitations for quantized oscillations of electrons. The resonant interaction between electron-charged oscillations near the surface of metal and the electromagnetic field creates SPs and results in rather unique properties. Recent studies in the visible spectral region have revealed that besides SPs, localized modes also make contributions to the extraordinary transmission in periodic subwavelength holes.
With the development of THz technology, it provides a new and powerful tool to study the optical and dielectric properties of various materials, such as bulk semiconductors, nanostructures, thin films, molecules, magnetic materials and so forth in THz region, as well as the THz transmission or reflection characteristics of many novel artificial structures. Here we would briefly present how to characterize materials of different forms by THz-TDS, which will involve in bulk, powder, thin film, molecules, magnetic material, metamaterial and artificial structures.