Abstract-High-efficiency terahertz polarization devices based on the dielectric metasurface

Jian Zhou, JingJing Wang, Kai Guo, Fei Shen,  Qingfeng Zhou,  Zhiping Yin,  Zhongyi Guo,



https://www.sciencedirect.com/science/article/pii/S0749603617327180

Metasurfaces are composed of the subwavelength structures, which can be used to manipulate the amplitude, phase, and polarization of incident electromagnetic waves efficiently. Here, we propose a novel type of dielectric metasurface based on crystal Si for realizing to manipulate the terahertz wave, in which by varying the geometric sizes of the Si micro-bricks, the transmitting phase of the terahertz wave can almost span over the entire 2π range for both of the x-polarization and y-polarization simultaneously, while keeping the similarly high-transmission amplitudes (over 90%). At the frequency of 1.0 THz, we have successfully designed a series of controllable THz devices, such as the polarization-dependent beam splitter, polarization-independent beam deflector and the focusing lenses based on the designed metasurfaces. Our designs are easy to fabricate and can be promising in developing high-efficiency THz functional devices.

Abstract-Actively Tunable Terahertz Switches Based on Subwavelength Graphene Waveguide

Zhongyi Guo, Xiaoru Nie, Fei Shen, Hongping Zhou, Qingfeng Zhou, Jun Gao, Kai Guo,

http://www.mdpi.com/2079-4991/8/9/665

As a new field of optical communication technology, on-chip graphene devices are of great interest due to their active tunability and subwavelength scale. In this paper, we systematically investigate optical switches at frequency of 30 THz, including Y-branch (1 × 2), X-branch (2 × 2), single-input three-output (1 × 3), two-input three-output (2 × 3), and two-input four-output (2 × 4) switches. In these devices, a graphene monolayer is stacked on the top of a PMMA (poly methyl methacrylate methacrylic acid) dielectric layer. The optical response of graphene can be electrically manipulated; therefore, the state of each channel can be switched ON and OFF. Numerical simulations demonstrate that the transmission direction can be well manipulated in these devices. In addition, the proposed devices possess advantages of appropriate ON/OFF ratios, indicating the good performance of graphene in terahertz switching. These devices provide a new route toward terahertz optical switching

Abstract-High-efficiency terahertz dual-function devices based on the dielectric metasurface

JingJing Wang, Jian Zhou, Kai Guo, Fei Shen, Qingfeng Zhou, Zhipingyin, Zhongyi Guo,




https://www.sciencedirect.com/science/article/pii/S0749603618308784

The multifunctional optical device has attracted great interests due to the wide range of modern optical applications. However, conventional optical devices are single function and bulky structure, thereby hindering the practicality and miniaturization of the optical systems. Here, we present the basic theory, simulated demonstration, and in-depth analysis of a novel type of dielectric metasurface based on crystal Si to simultaneously convert and focus an incident linear polarization into other linear polarization or circular polarization with high efficiency and high numerical aperture (NA). Additionally, we have also achieved a quart wave-plate (QWP) based deflector that enables both arbitrary anomalous beam deflection and the polarization conversion. Simulation results show that the invertible QWP based deflector, including the linear-to-circular (LTC) and circular-to-linear (CTL) conversions, demonstrate around 80% deflection efficiency at 1.0 THz. With similar concept, a half wave-plate (HWP) combined with beam steering has also been achieved. Taking into account the considerable manipulation efficiency and cost-efficient sample fabrication technique, our designs show the great potentials of metasurfaces as a versatile platform for designing practical functional devices in the THz range.

Abstract-High-efficiency terahertz polarization devices based on the dielectric metasurface

Jian Zhou,  JingJing Wang, Kai Guo, Fei Shen, Qingfeng Zhou, Zhiping Yin, Zhongyi Guo,

https://www.sciencedirect.com/science/article/pii/S0749603617327180

Metasurfaces are composed of the subwavelength structures, which can be used to manipulate the amplitude, phase, and polarization of incident electromagnetic waves efficiently. Here, we propose a novel type of dielectric metasurface based on crystal Si for realizing to manipulate the terahertz wave, in which by varying the geometric sizes of the Si micro-bricks, the transmitting phase of the terahertz wave can almost span over the entire 2π range for both of the x-polarization and y-polarization simultaneously, while keeping the similarly high-transmission amplitudes (over 90%). At the frequency of 1.0 THz, we have successfully designed a series of controllable THz devices, such as the polarization-dependent beam splitter, polarization-independent beam deflector and the focusing lenses based on the designed metasurfaces. Our designs are easy to fabricate and can be promising in developing high-efficiency THz functional devices.