A terahertz reconfigurable photo-induced fresnel-zone-plate antenna for dynamic two-dimensional beam steering and forming

Shams, Md. Itrat Bin; Jiang, Zhou; Qayyum, Jubaid Abdul; Rahman, Seikh Mohammad Habibur; Fay, Patrick; Liu, Lei

doi:10.1109/mwsym.2015.7167052

Cited by 12 publications

(9 citation statements)

References 14 publications

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“…To employ GaAs substrate for THz modulation, a high-power photoexcitation is required to generate sufficient excess carriers. A pulsed laser that delivers a few μJ/cm 2 energy in a 100 fs pulse duration with a period of picoseconds can equivalently produce a constantly high power density in the order of kW/cm 2 to MW/cm 2 to generate carriers satisfactory to THz modulation [13]. The large minority carrier lifetime in Si and Ge substrates allows generation of high carrier concentration with low-power photo-excitation, enabling the use of cost-effective light sources for THz modulation.…”

Section: Resultsmentioning

confidence: 99%

“…Among them, THz modulation through photo-induced carriers on a semiconductor using Digital Light Processing (DLP) projector is considered as a high-performance, reconfigurable and cost-effective approach [11,12]. This technique takes the advantages of optically generated conductive patterns on semiconductor substrates (e.g., silicon) to manipulate the transmission of THz waves, allowing one to perform a variety of reconfigurable functions, including THz beam steering [13], polarization, focusing and THz resonators. In spite of the success in the experimental demonstration of this technique, the modulation performance was found to be limited by plenty of factors, including the operating conditions and the choice of materials, which were not examined in the prior works.…”

Section: Introductionmentioning

confidence: 99%

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Photo-induced spatial modulation of THz waves: opportunities and limitations

Kannegulla¹,

Shams²,

Liu³

et al. 2015

Opt. Express

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Programmable conductive patterns created by photoexcitation of semiconductor substrates using digital light processing (DLP) provides a versatile approach for spatial and temporal modulation of THz waves. The reconfigurable nature of the technology has great potential in implementing several promising THz applications, such as THz beam steering, THz imaging or THz remote sensing, in a simple, cost-effective manner. In this paper, we provide physical insight about how the semiconducting materials, substrate dimension, optical illumination wavelength and illumination size impact the performance of THz modulation, including modulation depth, modulation speed and spatial resolution. The analysis establishes design guidelines for the development of photo-induced THz modulation technology. Evolved from the theoretical analysis, a new mesa array technology composed by a matrix of sub-THz wavelength structures is introduced to maximize both spatial resolution and modulation depth for THz modulation with low-power photoexcitation by prohibiting the lateral diffusion of photogenerated carriers.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Photo-induced spatial modulation of THz waves: opportunities and limitations

Kannegulla¹,

Shams²,

Liu³

et al. 2015

Opt. Express

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“…where q is the elementary charge, and μ e and μ h are the mobility of electrons and holes, respectively. This physics-based model for photoconductivity has been previously applied to the study of THz wave modulation depth [15][16][17][18]. Since the photoconductivity of the semiconductor can be controlled by the incident illumination, as shown in Eqs.…”

Section: Theories and Mechanisms Of Photo-induced Ebgmentioning

confidence: 99%

“…These two observations indicate that both stronger light intensity and thinner wafers lead to higher photoconductivity. As an example, for a Ge wafer with ∼ 100 µm thickness, ∼ 20 W/cm 2 light intensity (which can be readily provided by a commercially available DLP projector [17]) would lead to a photoconductivity of the order of 10 4 S/m, while over 200 W/cm 2 light intensity (which can be implemented by using a high power DLP projector, or using a high power laser diode in conjunction with a DMD chip [18]) would yield a photoconductivity of the order of 10 5 S/m. When high light intensity is required, heating effects may need to be considered in practice to ensure circuit stability and reliability.…”

Section: Theories and Mechanisms Of Photo-induced Ebgmentioning

confidence: 99%

“…In this paper, we investigate the performance potential of tunable and reconfigurable EBG components using a novel optical control methodology [15][16][17][18]. This approach is based on the generation of EBG structures through spatially-resolved photogeneration of free carriers in a semiconductor, without the need for complex fabrication processes.…”

Section: Introductionmentioning

confidence: 99%

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Photo-Induced Electromagnetic Band Gap Structures for Optically Tunable Microwave Filters

Ren¹,

Jiang²,

Shams³

et al. 2018

PIER

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Electromagnetic band gap (EBG) structures offer unique solutions for effectively manipulating electromagnetic waves over a broad range of frequencies for a wide range of applications. However, most EBG designs reported so far either require sophisticated fabrication processes or have limited tunability and reconfigurability. In this paper, we investigate the potential to implement high performance tunable and reconfigurable EBG components using a novel optical control approach. This technology allows the generation of EBG structures through spatially-resolved photogeneration of free carriers in a semiconductor, without any complex fabrication processes. As a prototype demonstration, a reconfigurable microwave frequency tunable band-stop filter (BSF) based on photo-induced uniplanar EBG structures has been investigated through simulation. In this approach, the required EBG patterns are directly illuminated onto a Ge ground plane mounted to the bottom of a Duroid substrate for tunability using a digital light processing (DLP) projector. On the basis of HFSS simulations, the bandwidth of the BSF can be tuned by modifying the EBG pattern filling factor. The center frequency of the BSF could also be tuned from 8-12 GHz by adjusting the period of the EBG structure. In addition, two limiting factors, i.e., localized heating effects and finite lateral spatial resolution (due to carrier diffusion), that may affect the circuit performance in this technology have been investigated and discussed. By using a mesa-array structured ground plane, this approach is promising for developing tunable and reconfigurable circuits such as filters from the microwave to terahertz regimes.

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Photo-Excited Silicon-Based Spatial Terahertz Modulators

Wang

Wen

2021

TST

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The increasing development of terahertz (THz) technology has led to various potential applications in THz imaging, spectroscopy and communications. These devices capable of actively manipulating the amplitude, phase and frequency of THz waves are thus gaining numerous interests. All-optical silicon-based spatial terahertz modulators (STMs), as a simple, cost-effective, and reconfigurable technique, are standing the focus of research. Beginning with a fundamental concept of THz radiation, this paper systematically summarized the modulation mechanism and theoretical model for this kind of STM, reviewed the recent advancements in THz functional devices implemented by this optical method and yet, discussed the performance-improved measures with an emphasis on the reflection reduction. Despite that, there has been considerable progress in realizing high-performance STMs, and novel design is urgent to realize higher modulation rate and more functionality.

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A terahertz reconfigurable photo-induced fresnel-zone-plate antenna for dynamic two-dimensional beam steering and forming

Cited by 12 publications

References 14 publications

Photo-induced spatial modulation of THz waves: opportunities and limitations

Photo-induced spatial modulation of THz waves: opportunities and limitations

Photo-Induced Electromagnetic Band Gap Structures for Optically Tunable Microwave Filters

Photo-Excited Silicon-Based Spatial Terahertz Modulators

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