Wednesday, December 13, 2017
Abstract-Comparison of digital beamforming algorithms for 3-D terahertz imaging with sparse multistatic line arrays
Bessem Baccouche, Patrick Agostini, Falco Schneider, Wolfgang Sauer-Greff, Ralph Urbansky, Fabian Friederich
In this contribution we compare the back-projection algorithm with our recently developed modified range migration algorithm for 3-D terahertz imaging using sparse multistatic line arrays. A 2-D planar sampling scheme is generated using the array's aperture in combination with an orthogonal synthetic aperture obtained through linear movement of the object under test. A stepped frequency continuous wave signal modulation is used for range focusing. Comparisons of the focusing quality show that results using the modified range migration algorithm reflect these of the back-projection algorithm except for some degradation along the array's axis due to the operation in the array's near-field. Nevertheless the highest computational efficiency is obtained from the modified range migration algorithm, which is better than the numerically optimized version of the back-projection algorithm. Measurements have been performed by using an imaging system operating in the W frequency band to verify the theoretical results.
Jingya Xie, Xi Zhu, Xiaofei Zang, Qingqing Cheng, Lin Chen, and Yiming Zhu
Tuesday, December 12, 2017
Abstract-Observation of Terahertz Radiation via the Two-Color Laser Scheme with Uncommon Frequency Ratios
Liang-Liang Zhang, Wei-Min Wang, Tong Wu, Rui Zhang, Shi-Jing Zhang, Cun-Lin Zhang, Yan Zhang, Zheng-Ming Sheng, and Xi-Cheng Zhang
H.M.Dong, F.Huang, W.Xu
We develop a simple theoretical approach to investigate terahertz (THz) optical properties of monolayer graphene in the presence of an external dc electric field. The analytical results for optical coefficients such as the absorptance and reflectivity are obtained self-consistently on the basis of a diagrammatic self-consistent field theory and a Boltzmann equilibrium equation. It is found that the optical refractive index, reflectivity and conductivity can be effectively tuned by not only a gate voltage but also a driving dc electric field. This study is relevant to the applications of graphene as advanced THz optoelectronic devices.