关键词: 太赫兹/
锑化铟/
磁表面等离子体/
聚焦
English Abstract
InSb based subwavelength array for terahertz wave focusing
Gu Wen-Hao,Chang Sheng-Jiang,
Fan Fei,
Zhang Xuan-Zhou
1.Institute of Modern Optics, Nankai University, Tianjin 300071, China
Fund Project:Project supported by the National Basic Research Program of China (Grant No. 2014CB339800), the National Natural Science Foundation of China (Grant Nos. 61171027, 61505088), the Natural Science Foundation of Tianjin, China (Grant No. 15JCQNJC02100), and the Project of Science and Technology Program of Tianjin, China (Grant No. 13RCGFGX01127).Received Date:24 August 2015
Accepted Date:24 September 2015
Published Online:05 January 2016
Abstract:With the continuous development of terahertz (THz) technology in recent years, many kinds of THz functional devices including switchers, filters, modulators, isolator and polarizers have been demonstrated. However, researches of the focusing devices in the terahertz frequency range are rarely reported. In this paper, we propose a subwavelength metal-air-InSb-metal periodic array structure to perform terahertz wave focusing. The dependence of permittivity of InSb in the THz regime on external magnetic field and temperature is calculated theoretically. Based on the magneto-optical effect of the semiconductor material InSb and asymmetrical waveguide structure, the influences of external magnetic field and temperature on the focusing and transmittance characteristics of the device are studied in detail. Numerically simulated results show that the structure proposed above can not only improve the transmittance greatly but also perform focusing perfectly. Calculations on the transmission properties show that in a certain range of temperature, the power flow transmittance at the focus point increases with the increase of temperature. In the meantime, for a certain temperature, with increasing the external magnetic field, the power flow continuously increases as well and reaches a maximum value at a certain magnetic field. For example, for a temperature of 172 K and a magnetic field of 0.6 T, the maximum power flow transmitted at the focus point is 10200 W/m2 at 0.8 THz, which is about 28 times larger than that without magnetic field at the same temperature. In addition, the simulation results also show that when the temperature and external magnetic field are fixed at 172 K and 0.5 T, respectively, the power flow transmittances for the incident waves at different frequencies are different. There is a peak value of the transmittance appearing at a specific frequency of 0.8 THz. Moreover, when the incident wave frequency is far from 0.8 THz, the transmittance decreases dramatically. It is worth noting that by choosing different temperatures and external magnetic fields, the structure proposed can not only enhance the transmittance over 20 times at the focus point, but also manipulate effectively the THz wave in a broad operating bandwidth of 400 GHz from 0.4 THz to 0.8 THz. These properties indicate that the proposed structure can act as an ideal tunable, broadband, and high transmittance focusing device in the terahertz regime.
Keywords: terahertz/
InSb/
magneto-plasmons/
focus
