Abstract-Resonance coupling and optical modulation properties in terahertz asymmetric double-wire structures

Ge Li, Qingli Zhou, Wanlin Liang, Cunlin Zhang,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10826/108261P/Resonance-coupling-and-optical-modulation-properties-in-terahertz-asymmetric-double/10.1117/12.2502510.short

The spectral characteristics of the asymmetric double-wire structures have been investigated in the terahertz (THz) range. Based on the THz time-domain spectroscopy system, the spectral of the samples has been measured. It is shown that a transparent peak appears in the transmission spectrum which indicate that a resonance coupling exist between the two metal bars. Furthermore, we study the optical modulation properties when the pump light irradiates on the sample by using optical pump-terahertz probe technique (OPTP). The measured results indicate that the pump light can realize an optical switch effect to modulate the transmittance of THz wave. When adjusting the time delay between the optical pump and the terahertz probe pulses, the transmittance of THz wave varies, indicating the photoexcited carriers in the substrate have great influence on the resonance characteristics of the structure. Our obtained results indicate optical modulation method could provide the functionally potential applications in the terahertz modulators and filters.

© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-Study on asymmetric terahertz metamaterials for biosensing

Wanlin Liang, Qingli Zhou, Ge Li, Cunlin Zhang

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10826/108261Q/Study-on-asymmetric-terahertz-metamaterials-for-biosensing/10.1117/12.2502511.short

Recently, the terahertz biosensors based on metamaterials have attracted much attention due to the fact that metamaterials are sensitive to the local enhancement of electromagnetic field and the changes of the surrounding dielectric environment. In order to obtain the resonances with the high quality factor for biosensing, here we designed, simulated, and fabricated the metamaterial structures composed of a series of the asymmetric “double” circular arc (DASR) structures. The experimental data show there are three sharp resonance dips named Fano resonance in the terahertz transmission spectra. In the previous study of asymmetric double rings, we studied the effect of different cutting widths on the transmission characteristics of terahertz when the samples were placed at 0 degrees. Here, the spectral characteristics and polarization conversion characteristics of the samples after 90 degrees were studied. We found that when the sample rotated by 90 degrees only two resonance dips exist in the transmission spectrum. As the separation of asymmetric arcs gradually increases, two resonance frequencies also show blue-shift. To further analyze the reasons for the changes in the transmission spectrum at different angles of sample placement, we present the surface currents and the electromagnetic field distributions in those structures. Our obtained results indicate the terahertz metamaterial has great potential in application of biosensing field.

© (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.