Diffraction of terahertz waves after passing through a Fresnel lens
Shi Yu-Lei(施宇蕾),Zhou Qing-Li(周庆莉)†, and Zhang Cun-Lin (张存林)
Beijing Key Laboratory for Terahertz Spectroscopy and Imaging, Key Laboratory of Terahertz Optoelectronics, Ministry of Education, Department of Physics, Capital Normal University, Beijing 100048, China
Abstract The spatiotemporal and spectral characteristics of ultrawide-band terahertz pulses after passing through a Fresnel lens are studied by using the scalar diffraction theory. The simulation shows that the transmitted terahertz waveforms compress with increasing propagation distance, and the multi-frequency focusing phenomenon at different focal points is observed. Additionally, the distribution of terahertz fields in a plane perpendicular to the axis is also discussed, and it is found that the diffraction not only induces focusing on-axis but also inhibits focusing at off-axis positions. Therefore, the Fresnel lens may be a useful alternative approach to being a terahertz filter. Moreover, the terahertz pulses travelling as a basic mode of a Gaussian beam are discussed in detail.
Received: 16 June 2009
Revised: 25 July 2009
Accepted manuscript online:
(Radiowave and microwave (including millimeter wave) technology)
Fund: Project supported by the National
Basic Research Program of China (Grant Nos 2007CB310408 and
2006CB302901), the National Natural Science Foundation of China
(Grant No 10804077), Beijing Municipal Commission of Education
(Grant No KM200910028006), Funding
Cite this article:
Shi Yu-Lei(施宇蕾),Zhou Qing-Li(周庆莉), and Zhang Cun-Lin (张存林) Diffraction of terahertz waves after passing through a Fresnel lens 2009 Chin. Phys. B 18 5511
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