中国物理B ›› 2009, Vol. 18 ›› Issue (12): 5511-5517.doi: 10.1088/1674-1056/18/12/064

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Diffraction of terahertz waves after passing through a Fresnel lens

施宇蕾, 周庆莉, 张存林   

  1. 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
  • 收稿日期:2009-06-16 修回日期:2009-07-25 出版日期:2009-12-20 发布日期:2009-12-20
  • 基金资助:
    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

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)   

  1. 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
  • Received:2009-06-16 Revised:2009-07-25 Online:2009-12-20 Published:2009-12-20
  • Supported by:
    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

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摘要： 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.

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.

Key words: terahertz, Fresnel lens, diffraction field

中图分类号:  (Diffraction and scattering)

  • 42.25.Fx
07.57.Pt (Submillimeter wave, microwave and radiowave spectrometers; magnetic resonance spectrometers, auxiliary equipment, and techniques) 42.79.Bh (Lenses, prisms and mirrors) 84.40.-x (Radiowave and microwave (including millimeter wave) technology)