Abstract-Achromatic terahertz Airy beam generation with dielectric metasurfaces

 

Qingqing Cheng , Juncheng Wang, Ling Ma, Zhixiong Shen, Jing Zhang, Xiaoying Zheng ,Tao Chen, Ye Yu, Dong Yu, Qiong He, Wei Hu, Tao Li, Songlin Zhuang,  Lei Zhou

https://www.degruyter.com/view/journals/nanoph/ahead-of-print/article-10.1515-nanoph-2020-0536/article-10.1515-nanoph-2020-0536.xml?rskey=WV2s5h&result=7&tab_body=abstract

Airy beams exhibit intriguing properties such as nonspreading, self-bending, and self-healing and have attracted considerable recent interest because of their many potential applications in photonics, such as to beam focusing, light-sheet microscopy, and biomedical imaging. However, previous approaches to generate Airy beams using photonic structures have suffered from severe chromatic problems arising from strong frequency dispersion of the scatterers. Here, we design and fabricate a metasurface composed of silicon posts for the frequency range 0.4–0.8 THz in transmission mode, and we experimentally demonstrate achromatic Airy beams exhibiting autofocusing properties. We further show numerically that a generated achromatic Airy-beam-based metalens exhibits self-healing properties that are immune to scattering by particles and that it also possesses a larger depth of focus than a traditional metalens. Our results pave the way to the realization of flat photonic devices for applications to noninvasive biomedical imaging and light-sheet microscopy, and we provide a numerical demonstration of a device protocol.

Abstract-Exposure Effects of Terahertz Waves on Primary Neurons and Neuron-like Cells Under Nonthermal Conditions

Sheng Zhi Tan, Peng Cheng Tan , Lan Qing Luo , Yun Liang Chi , Zi Long Yang , Xue Long Zhao , Li Zhao, Ji Dong, Jing Zhang, , Bin Wei Yao, Xin Ping Xu, Guang Tian , Jian Kui Chen, Hui Wang, Rui Yun Peng,

http://www.besjournal.com/en/article/doi/10.3967/bes2019.094

Objective: This study aimed to explore the potential effects of terahertz (THz) waves on primary cultured neurons from 4 rat brain regions (hippocampus, cerebral cortex, cerebellum, and brainstem) and 3 kinds of neuron-like cells (MN9D, PC12, and HT22 cells) under nonthermal conditions.

Methods: THz waves with an output power of 50 (0.16 THz) and 10 (0.17 THz) mW with exposure times of 6 and 60 min were used in this study. Analysis of temperature change, neurite growth, cell membrane roughness, micromorphology, neurotransmitters and synaptic-related proteins (SYN and PSD95) was used to evaluate the potential effects.

Results: Temperature increase caused by the THz wave was negligible. THz waves induced significant neurotransmitter changes in primary hippocampal, cerebellar, and brainstem neurons and in MN9D and PC12 cells. THz wave downregulated SYN expression in primary hippocampal neurons and downregulated PSD95 expression in primary cortical neurons.

Conclusion: Different types of cells responded differently after THz wave exposure, and primary hippocampal and cortical neurons and MN9D cells were relatively sensitive to the THz waves. The biological effects were positively correlated with the exposure time of the THz waves.

Copyright © 2019 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Abstract-Effect of optical pumping on the dielectric properties of 0.6CaTiO3-0.4NdAlO3 ceramics in the terahertz range

Dan Li, Chunya Luo, Yebin Xu, Jing Zhang, Liang Wu, Huaixing Wang, Songjie Shi, Furi Ling, and Jianquan Yao

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-57-1-1&origin=search

The dielectric properties of 0.6CaTiO3-0.4NdAlO3$0.6{\mathrm{CaTiO}}_3\text{-}0.4{\mathrm{NdAlO}}_3$ ceramics under external optical fields were investigated by terahertz time-domain spectroscopy in a frequency range of 0.2 THz to 1 THz at room temperature. It could be found that the variation of the real part of complex permittivity is approximately 0.31 in the frequency range of 0.2 THz to 1 THz. However the imaginary part of the dielectric constant does not change appreciably with the external optical field. The micromechanism of these results was attributed to the built-in electric field caused by the excited free carriers in the ceramics.

© 2017 Optical Society of America