scholarly journals Full 360° Terahertz Dynamic Phase Modulation Based on Doubly Resonant Graphene–Metal Hybrid Metasurfaces

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3157
Author(s):  
Binxu Wang ◽  
Xiaoqing Luo ◽  
Yalin Lu ◽  
Guangyuan Li
Keyword(s):  
Fermi Energy ◽  
Phase Modulation ◽  
Beam Steering ◽  
Terahertz Waves ◽  
Dynamic Phase ◽  
Phase Profile ◽  
Profile Design ◽  
Simulation Results ◽  
High Reflectance ◽  
Dynamic Manipulation

Dynamic phase modulation is vital for tuneable focusing, beaming, polarisation conversion and holography. However, it remains challenging to achieve full 360° dynamic phase modulation while maintaining high reflectance or transmittance based on metamaterials or metasurfaces in the terahertz regime. Here, we propose a doubly resonant graphene–metal hybrid metasurface to address this challenge. Simulation results show that by varying the graphene Fermi energy, the proposed metasurface with two shifting resonances is capable of providing dynamic phase modulation covering a range of 361° while maintaining relatively high reflectance above 20% at 1.05 THz. Based on the phase profile design, dynamically tuneable beam steering and focusing were numerically demonstrated. We expect that this work will advance the engineering of graphene metasurfaces for the dynamic manipulation of terahertz waves.

scholarly journals Full 360∘ Terahertz Dynamic Phase Modulation Based on Doubly Resonant Graphene-Metal Hybrid Metasurfaces

2021 ◽  
Author(s):  
Binxu Wang ◽  
Xiaoqing Luo ◽  
Yalin Lu ◽  
Guangyuan Li
Keyword(s):  
Fermi Energy ◽  
Phase Modulation ◽  
Beam Steering ◽  
Polarization Conversion ◽  
Terahertz Waves ◽  
Dynamic Phase ◽  
Phase Profile ◽  
Profile Design ◽  
Simulation Results ◽  
High Reflectance

Dynamic phase modulation is vital for tunable focusing, beaming, polarization conversion and holography. However, it remains challenging to achieve full 360∘ dynamic phase modulation while maintaining high reflectance or transmittance based on metamaterials or metasurfaces in the terahertz regime. Here we propose a doubly resonant graphene-metal hybrid metasurface to address this challenge. Simulation results show that by varying the graphene Fermi energy, the proposed metasurface with two shifting resonances is capable to provide dynamic phase modulation covering a range of 361∘ while maintaining relatively high reflectance above 20% at 1.05 THz. Based on the phase profile design, dynamically tunable beam steering and focusing are numerically demonstrated. We expect this work will advance the engineering of graphene metasurfaces for the dynamic manipulation of terahertz waves.

A Linear Acoustic Phased Array for Nonreciprocal Transmission and Reception

2020 ◽  
Author(s):  
R. Adlakha ◽  
M. Moghaddaszadeh ◽  
M. A. Attarzadeh ◽  
A. Aref ◽  
M. Nouh
Keyword(s):  
Phase Modulation ◽  
Frequency Conversion ◽  
Phased Array ◽  
Space Time ◽  
Mathematical Framework ◽  
Sound Waves ◽  
Asymmetric Transmission ◽  
Time Modulation ◽  
Dynamic Phase ◽  
Phase Angles

Abstract Acoustic phased arrays are capable of steering and focusing a beam of sound via selective coordination of the spatial distribution of phase angles between multiple sound emitters. Here, we propose a controllable acoustic phased array with space-time modulation that breaks time-reversal symmetry, and enables phononic transition in both momentum and energy spaces. By leveraging the dynamic phase modulation, the proposed linear phased array is no longer bound by the reciprocity principle, and supports asymmetric transmission and reception patterns that can be tuned independently. Through theoretical and numerical investigations, we develop and verify a mathematical framework to characterize the nonreciprocal phenomena, and analyze the frequency conversion between the wave fields. The space-time acoustic phased array facilitates unprecedented control over sound waves in a variety of applications including underwater telecommunication.

scholarly journals Terahertz Beam Steering Concept Based on a MEMS-Reconfigurable Reflection Grating

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2874
Author(s):  
Xuan Liu ◽  
Lisa Samfaß ◽  
Kevin Kolpatzeck ◽  
Lars Häring ◽  
Jan C. Balzer ◽  
...  
Keyword(s):  
Diffraction Grating ◽  
High Speed ◽  
Beam Steering ◽  
Vertical Displacement ◽  
Grating Period ◽  
Terahertz Waves ◽  
Large Area ◽  
Electrostatic Actuators ◽  
Reflection Gratings ◽  
Reflection Grating

With an increasing number of applications of terahertz systems in industrial fields and communications, terahertz beamforming and beam steering techniques are required for high-speed, large-area scanning. As a promising means for beam steering, micro-electro-mechanical system (MEMS)-based reflection gratings have been successfully implemented for terahertz beam control. So far, the diffraction grating efficiency is relatively low due to the limited vertical displacement range of the reflectors. In this paper, we propose a design for a reconfigurable MEMS-based reflection grating consisting of multiple subwavelength reflectors which are driven by 5-bit, high-throw electrostatic actuators. We vary the number of the reflectors per grating period and configure the throw of individual reflectors so that the reflection grating is shaped as a blazed grating to steer the terahertz beam with maximum diffraction grating efficiency. Furthermore, we provide a mathematical model for calculating the radiation pattern of the terahertz wave reflected by general reflection gratings consisting of subwavelength reflectors. The calculated and simulated radiation patterns of the designed grating show that we can steer the angle of the terahertz waves in a range of up to ± 56.4 ∘ with a maximum sidelobe level of −10 dB at frequencies from 0.3 THz to 1 THz.

An acoustic metasurface with simultaneous phase modulation and energy attenuation

2018 ◽  
Vol 32 (23) ◽  
pp. 1850276 ◽  
Author(s):  
Baozhu Cheng ◽  
Hong Hou ◽  
Nansha Gao
Keyword(s):  
Phase Modulation ◽  
Low Frequency ◽  
Layered Media ◽  
Media Theory ◽  
Wave Direction ◽  
Medium Theory ◽  
Underwater Acoustic ◽  
Potential Applications ◽  
Simulation Results ◽  
Effective Phase

We introduced a rigid structure into the acoustic metasurface design, the proposed labyrinth structure is based on the equivalent medium theory and different media are replaced by curly labyrinth. Layered media theory and equivalent medium theory are combined to design the arbitrary acoustic metasurface structure. An acoustic metasurface studied in this paper realized simultaneous phase modulation and energy attenuation in the air, the effective phase modulation range covered from 30[Formula: see text] to 90[Formula: see text] and the energy attenuation is over 40%. According to layered media theory which could modulate the acoustic wave direction, the metasurface with same function can also be applied to underwater case. Corresponding simulation results are calculated by FEA. Finally, by introducing the curly labyrinth theory, the underwater acoustic metasurface with simultaneous phase modulation and energy attenuation is designed and verified. This paper has potential applications in rigid underwater acoustic metasurface designs with low frequency, adjustable direction and sound energy attenuation.

Rate-Compatible Punctured Ring Convolutional Coded Continuous Phase Modulation

2012 ◽  
Vol 195-196 ◽  
pp. 217-220
Author(s):  
Lei Zhang ◽  
Man Ping Tong ◽  
Hong Bo Wang
Keyword(s):  
Bit Error Rate ◽  
Error Rate ◽  
Phase Modulation ◽  
Euclidean Distance ◽  
Convolutional Codes ◽  
Continuous Phase ◽  
Transmission Efficiency ◽  
Continuous Phase Modulation ◽  
Simulation Results ◽  
Squared Euclidean Distance

In this paper, continuous phase modulation (CPM) with rate-compatible punctured ring convolutional codes is investigated. Some typical schemes with maximum normalized minimum squared euclidean distance (NMSED) are searched and given. The performance of bit error rate for rate-compatible punctured ring convolutional coded CPM on AWGN channel is simulated, and simulation results show that this system can provide good performance of bit error rate and variable-rate capabilities. Furthermore, simulation results also prove that the transmission efficiency increases when code rate is decreasing.

scholarly journals Электронные и теплофизические свойства газовых гидратов: результаты моделирования из первых принципов

2021 ◽  
Vol 63 (2) ◽  
pp. 308
Author(s):  
М.Б. Юнусов ◽  
Р.М. Хуснутдинов ◽  
А.В. Мокшин
Keyword(s):  
Fermi Energy ◽  
Methane Hydrate ◽  
Energy Spectra ◽  
Ab Initio Molecular Dynamics ◽  
Fermi Energy Level ◽  
Density Of Electronic States ◽  
Level Width ◽  
Temperature Dependences ◽  
Simulation Results ◽  
Good Agreement

The results of an ab-initio molecular dynamics study of the electronic and thermophysical properties of methane hydrate with a cubic sI structure are presented. Good agreement of the simulation results for heat capacity at constant volume and density with experimental data is found. Based on the analysis of the density of electronic states, the temperature dependences of the electronic properties of methane hydrate, including the Fermi energy level, width and boundaries of the band gap are determined. For the empty framework of the hydrate (water clathrate framework), the electron energy spectra E(k) were calculated along the directions M-X, X-G, G-M, and G-R. It was found that the presence of CH4 molecules in an aqueous clathrate leads to an increase in the Fermi energy of the hydrate from 2.4 to 3.0 eV.

scholarly journals Photonics-Assisted Terahertz-Wave Beam Steering and Its Application in Secured Wireless Communication

Photonics ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 9
Author(s):  
Kazutoshi Kato
Keyword(s):  
Wireless Communication ◽  
Power Efficiency ◽  
Electromagnetic Waves ◽  
High Speed ◽  
Phased Array ◽  
Beam Steering ◽  
Terahertz Wave ◽  
Coherent Detection ◽  
Terahertz Waves ◽  
Optical Domain

Beam forming and beam steering are inevitable technologies for the practical application of high-frequency electromagnetic waves. Specifically, beam control technology using a phased array for terahertz waves above 100 GHz is necessary to realize the future of high-speed wireless communication. By photomixing, which is a promising method for generating terahertz waves, the phase of the generated waves can be tuned in the optical domain, so that the beam from the phased array can be controlled by photonics technologies. Directing the beam of a terahertz wave enables wireless communication to be improved not only via an increase in power efficiency but also in security in the physical layer of the wireless transmission. By utilizing this advantage and using coherent detection at the receiver, a secured wireless communication system is proposed, and the fundamental mechanism is demonstrated in a feasibility experiment.

scholarly journals High Precision Optical Wavefront Generation Using Liquid Crystal Spatial Light Modulator (LC-SLM)

2021 ◽  
Author(s):  
Zixin Zhao
Keyword(s):  
Liquid Crystal ◽  
Future Development ◽  
Phase Modulation ◽  
Phase Response ◽  
Crystal Layer ◽  
Liquid Crystal Layer ◽  
Light Modulator ◽  
Phase Profile ◽  
Modulated Phase ◽  
State Of Art

LC-SLM provides a flexible way to modulate the phase of light with the help of a grayscale pattern loaded on it. Nevertheless, the modulated phase profile is of relatively low accuracy due to the nonlinear and nonuniform response of the liquid crystal layer in the SLM. To improve the performance of LC-SLM on the wavefront generation, the nonlinear and nonuniform phase response needs to be calibrated and compensated effectively. In this chapter, we present some state-of-art methods to measure the phase modulation curve of the LC-SLM. Some methods to measure the static aberration caused by the backplane of the LC-SLM are then presented. Last but not the least, the future development of the LC-SLM in phase modulation is also presented.

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