Sunday, April 23, 2017

US Patent Application and Abstract-Terahertz modulator based on low-dimension electron plasma wave and manufacturing method thereof

USPTO Applicaton #: #20170108756 
Inventors: Yongdan HuangHua QinZhipeng ZhangYao Yu

A terahertz modulator based on low-dimension electron plasma wave, a manufacturing method thereof, and a high speed modulation method are provided. The terahertz modulator includes a plasmon and a cavity. The present disclosure discloses the resonance absorption mechanism caused by collective oscillation of electrons (plasma wave, namely, the plasmon). In order to enhance the coupling strength between the terahertz wave and the plasmon, a GaN/AlGaN high electron mobility transistor structure having a grating gate is integrated in a terahertz Fabry-Pérot cavity, and a plasmon polariton is formed arising from strong coupling of the plasmon and a cavity mode.

Abstract- Broadband and Robust Metalens with Nonlinear Phase Profiles for Efficient Terahertz Wave Control

Quanlong Yang, Jianqiang Gu, Yuehong Xu, Xueqian Zhang, Yanfeng Li, Chunmei Ouyang, Zhen Tian, Jiaguang Han, Weili Zhang,

Metasurfaces, 2D artificial electromagnetic media, open up a new frontier of functional device design ranging from radio waves to the visible region. Particularly, metasurface-based lenses are indispensable in various practical terahertz applications. The authors aim at achieving flexible and robust metalenses for efficient terahertz wave control. In general, resolution and efficiency are two inevitable parameters in determining the focusing and imaging abilities of lenses, which however are rarely experimentally demonstrated in the terahertz band. In this Communication, three broadband and robust metalenses with nonlinear phase profiles are proposed, all of which are experimentally investigated by using near-field scanning terahertz microscopy (NSTM) with a spatial resolution of 50 µm. The measurement shows that the metalens can focus a 0.95 THz wave to a spot size of 580 µm and achieve a transmittance efficiency of 45%. In addition, the NSTM system facilitates an experimental investigation of the incidence angle dependence of the terahertz metalens, which proves the robust focusing feature of the proposed device. This demonstration delivers a promising metasurface design for potential applications in imaging and information processing that may be of interest for the entire electromagnetic spectrum.

Saturday, April 22, 2017

Abstract-Design and Fabrication of Waveguide Optics for Imaging Applications

Due to the non-ionizing property, researchers have chosen to investigate terahertz radiation (THz) Imaging instrumentation for Bio-Sensing applications. The present work is to design and fabricate a near field lens that can focus guided terahertz radiation to a microscopic region for the detection of cancer-affected cells in Biological tissue. Operational characteristics such as field of view, optical loss factor, and hydrophobicity must be included to achieve an effective design of the lens.

Abstract-Direct visualization of light confinement and standing wave in THz Fabry-Perot resonator with Bragg mirrors

Chongpei Pan, Qiang Wu, Qi Zhang, Wenjuan Zhao, Jiwei Qi, Jianghong Yao, Chunling Zhang, W. T. Hill, and Jingjun Xu

We report for the first time the ability to perform time resolved imaging of terahertz (THz) waves propagating within a Fabry-Perot resonator on a LiNbO3 slab. Electro-optic effect is used to record the full spatiotemporal evolution of THz fields inside the resonator. In addition to revealing the real-space behavior, the data further demonstrate the confinement and the standing wave modes of THz in the cavity in frequency domain. The experimental results are in good agreement with numerical simulations. Using the coherent imaging technique to gain real-time information about a resonator system provides a unique path to study the physics of optical cavity.
© 2017 Optical Society of America

Friday, April 21, 2017

Abstract-Quantized photonic spin Hall effect in graphene

Liang Cai, Mengxia Liu, Shizhen Chen, Yachao Liu, Weixing Shu, Hailu Luo, and Shuangchun Wen

We examine the photonic spin Hall effect (SHE) in a graphene-substrate system with the presence of an external magnetic field. In the quantum Hall regime, we demonstrate that the in-plane and transverse spin-dependent splittings in the photonic SHE exhibit different quantized behaviors. The quantized SHE can be described as a consequence of a quantized geometric phase (Berry phase), which corresponds to the quantized spin-orbit interaction. Furthermore, an experimental scheme based on quantum weak value amplification is proposed to detect the quantized SHE in the terahertz frequency regime. By incorporating the quantum weak measurement techniques, the quantized photonic SHE holds great promise for detecting quantized Hall conductivity and the Berry phase. These results may bridge the gap between the electronic SHE and photonic SHE in graphene.
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