Terahertz photoconductive antenna based on antireflection dielectric metasurfaces with embedded plasmonic nanodisks

Jiang, Xiaoqiang; Fan, Wenhui; Song, Chao; Chen, Xu; Wu, Qi

doi:10.1364/ao.431678

Cited by 5 publications

(2 citation statements)

References 40 publications

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“…Typical examples of such materials include silicon, gallium arsenide, silicon carbide, and lead sulfide. Typically, a photoconductive metasurface consists of a pair of metal contacts placed on a photosensitive semiconductor substrate (photoconductor) [115], as depicted in Fig. 12.…”

Section: B Intelligent Metasurface Reflector (Imr): From the Physics ...mentioning

confidence: 99%

RIS-Assisted Visible Light Communication Systems: A Tutorial

Aboagye¹,

Ndjiongue²,

Ngatched³

et al. 2022

Preprint

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Recent intensive and extensive development of the fifth-generation (5G) of cellular networks has led to their deployment throughout much of the world. As part of this implementation, one of the challenges that must be addressed is the skip-zone problem, which occurs when objects such as trees, people, animals, and vehicles obstruct the transmission of signals.In free-space optical (FSO) and radio frequency (RF) systems, dead zones are most often caused by buildings and trees, while in visible light communications (VLC), obstructions are caused by individuals moving around a room or objects placed in the room. A signal obstruction can significantly reduce the signal-to-noise ratio in RF and indoor VLC systems, whereas in FSO systems, where the transmitted signals are directional, the obstruction can completely disrupt data transmission. Therefore, the skipzone dilemma must be resolved to ensure the smooth and efficient operation of 5G and beyond networks. By placing a relay between a transmitter and a receiver, the effects of obstacles can be mitigated. As a result, the signal from the transmitter will reach the receiver. In recent years, reconfigurable intelligent surfaces (RISs) that are more efficient than relays have become widely accepted as a method of mitigating skip-zones and providing reconfigurable radio environments. However, there have been limited studies on RISs for optical wireless communication (OWC) systems. Through the RIS technology, OWC and RF communication channels can be reconfigured. This paper aims to provide a comprehensive tutorial on indoor VLC systems utilizing RIS technology. The article discusses the basics of VLC and RISs and reintroduces RISs for OWC systems, focusing on RIS-assisted indoor VLC systems. We also provide a comprehensive overview of optical RISs and examine the differences between optical RISs, RF-RISs, and optical relays. Furthermore, we discuss in detail how RISs can be used to overcome line-of-sight blockages and the device orientation issue in VLC systems while revealing key challenges such as RIS element orientation design, RIS elements to access point/user assignment design, and RIS array positioning design problems that need to be studied. Moreover, we discuss and propose several research problems on integrating optical RISs with other emerging technologies, including non-orthogonal multiple access, multiple-input multiple-output systems, physical layer security, and simultaneous lightwave and power transfer in VLC systems. Finally, we highlight other important research directions that can further improve the performance of RISassisted VLC systems.

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Section: B Intelligent Metasurface Reflector (Imr): From the Physics ...mentioning

confidence: 99%

RIS-Assisted Visible Light Communication Systems: A Tutorial

Aboagye¹,

Ndjiongue²,

Ngatched³

et al. 2022

Preprint

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“…Isgandarov et al [12] reviewed the two types of the large-aperture photoconductive antenna (LAPCA) that could generate high-intensity THz pulses (a) those with large-aperture dipoles and (b) those with interdigitated electrodes. Jiang et al [13] conducted a detailed study on the designed GaAs dielectric metasurfaces with embedded plasmonic nanodisks and obtained the optical reflection down to 1.4% and broadened THz spectrum emitted from THz-PCA. On the other hand, in a scheme where two interdigitated finger electrodes are used on a semi-insulating surface of a 5-micron with the biased voltage, the direction of the electric field is reversed between the successive electrodes, creating destructive interference.…”

Section: Introductionmentioning

confidence: 99%

Terahertz Radiation Generation by Laser Interaction with a Periodic Array of GaAs Structure

Sandeep

Malik

2023

Preprint

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In the current study, a method for generating terahertz (THz) radiation using a GaAs structure array and transient current from a laser is proposed. The current generated across the length of these structures is responsible for the generation of THz radiation, where the entire system acts as phase-array dipole antennae. The maximum emitted THz power is achieved in the directions, where the conditions −bd/𝑐 𝑠𝑖𝑛𝜃𝑐𝑜𝑠𝜙=𝑝1𝜋 and −bd/𝑐 𝑠𝑖𝑛𝜃=𝑝2𝜋 are met; b and d are the widths and the length of a single GaAs structure and p1 and p2 are the integers. Where M1 and M2 are the numbers of GaAs structures along the longitudinal and transverse directions of the laser propagation, respectively, the overall antenna gain is observed to be M12 M22in these directions. The antennae approach used for the proposed GaAs periodic array enables us to obtain the THz profile in the frequency domain and realize the role of arrays and size of GaAs structure, making the emitted radiation suitable for its THz Time Domain Spectroscopic applications.

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