Abstract-Abruptly autofocusing terahertz waves with meta-hologram

Abruptly autofocusing terahertz waves with meta-hologram

ingwen He, Sen Wang, Zhenwei Xie, Jiasheng Ye, Xinke Wang, Qiang Kan, and Yan Zhang

https://www.osapublishing.org/ol/abstract.cfm?uri=ol-41-12-2787

An abruptly autofocusing ring-Airy beam is demonstrated in the terahertz (THz) waveband with a meta-hologram. The designed meta-hologram is composed of gold C-shaped slot antennas, which can realize both phase and amplitude modulation of the incident THz wave. A THz holographic imaging system is utilized to measure the generated ring-Airy beam; an abrupt focus following a parabolic trajectory is subsequently observed. THz ring-Airy beams with different parameters are also generated and investigated. This method can be expanded to other wavebands, such as the visible band, for which the meta-hologram can replace traditional computer-generated holography to avoid undesirable multiple diffraction orders.

© 2016 Optical Society of America

Abstract-Generation of terahertz vector beams with a concentric ring metal grating and photo-generated carriers

Generation of terahertz vector beams with a concentric ring metal grating and photo-generated carriers Zhenwei Xie, Jingwen He, Xinke Wang, Shengfei Feng, and Yan Zhang  »View Author Affiliations

Optics Letters, Vol. 40, Issue 3, pp. 359-362 (2015)
http://dx.doi.org/10.1364/OL.40.000359

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-40-3-359

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A scheme for vector terahertz (THz) beam generation is proposed. A subwavelength metal grating is utilized to adjust the polarization of the THz radiation. The amplitude and phase distributions of the THz beam are dynamically regulated by a THz computer-generated hologram (CGH) pattern of the photo-generated carriers. A radially polarized THz beam and a vector THz vortex beam with a topological charge of 1 are generated to demonstrate the validity and the effectiveness of the proposed scheme. Experimental results correspond to the theoretical simulations well. Moreover, the proposed method is applicative for a broadband THz radiation. These results could be applied in the THz sensing, THz imaging, and THz communication in the future.

© 2015 Optical Society of America

Abstract-Full vector measurements of converging terahertz beams with linear, circular, and cylindrical vortex polarization

Xinke Wang, Sen Wang, Zhenwei Xie, Wenfeng Sun, Shengfei Feng, Ye Cui, Jiasheng Ye, and Yan Zhang  »View Author Affiliations

Optics Express, Vol. 22, Issue 20, pp. 24622-24634 (2014)
http://dx.doi.org/10.1364/OE.22.024622

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-20-24622

The complete vector information of converging terahertz (THz) beams with linear, circular, and cylindrical vortex polarization are precisely measured by using a THz digital holographic imaging system. The transverse (Ex, Ey) and longitudinal (Ez) polarization components of the THz fields around the focal point are separately obtained utilizing the detection crystals with different crystalline orientations. The measured results are in good agreement with the theoretical expectations. This imaging technique provides an effective way for revealing the vector diffraction properties of the THz electro-magnetic waves.

© 2014 Optical Society of America

Abstract-Focusing and imaging of a virtual all-optical tunable terahertz Fresnel zone plate

Xinke Wang, Zhenwei Xie, Wenfeng Sun, Shengfei Feng, Ye Cui, Jiasheng Ye, and Yan Zhang  »View Author Affiliations
http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-38-22-4731

A virtual all-optical tunable terahertz Fresnel zone plate is achieved utilizing the localized distribution of the transient electron plasma on a silicon wafer. Its focusing and imaging performance are experimentally demonstrated. Experimental results show that the effect of the virtual zone plate is the same as an actual one. Adjusting the spatial pattern of the electron plasma, the central wavelength and the focal length of the virtual zone plate can be all-optically dynamically steered. The research is a significant step to the development of tunable optical imaging elements.

© 2013 Optical Society of America