Continuous terahertz wave generation based on photomixers coupled to Fibonacci fractal tree antennas

Jafari, Hamed Mazhab; Heidarzadeh, Hamid; Rostami, G.; Dolatyari, Mahboubeh; Rostami, Ali

doi:10.1007/s11082-016-0810-9

Cited by 4 publications

(4 citation statements)

References 25 publications

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“…The peak amplitude of the THz backward emission reaches 0.0034 normalized by m𝜔 0 c∕e with 𝜔 0 the incident laser frequency, which equals to 0.137 GV cm −1 . The wavelength of the backward emission is about 30 𝜇m, thus the corresponding central frequency is around 10 THz, which collaborates with the plasma frequency in the interacting area (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). As the plasma density in the channel is inhomogeneous transversely, the wavevector of the wakefield induced by a laser beam with finite beam diameter near the entrance inside the channel is no longer parallel to the x-direction, as shown in Figure 2a.…”

Section: Two Terahertz Emission Modes From Plasma Channels With An Of...mentioning

confidence: 76%

“…Due to limitation of material breakdown under high laser field excitation, however, it is difficult to obtain powerful THz emission with typical laser-based schemes involving conventional optical materials, e.g., electrooptical crystals, [9] or photoconductive antennas. [10] Laser-plasma filaments in air and gas media have been widely investigated as a high-power THz source, which results from photon ionization currents and may achieve a field strength of above MV cm −1 . [11][12][13][14] However, the corresponding photon energy conversion efficiency is as low as 10 −4 .…”

Section: Introductionmentioning

confidence: 99%

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Tunable High‐Field Terahertz Radiation from Plasma Channels

Wang

Chen

Zhang

et al. 2023

Laser & Photonics Reviews

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Tunable broadband terahertz (THz) sources with power at the gigawatt level are desirable for many applications. A scheme to generate such THz emission by off-axially injecting a weakly relativistic ultrashort laser into a parabolic plasma channel is presented. By utilizing two-dimensional particle-in-cell simulation, it is demonstrated that there are two major physical mechanisms involved, i.e., linear mode conversion from laser wakefields and the electromagnetic waveguide mode excitation inside the plasma channel. The two radiation modes can lead to linearly polarized and radially polarized THz emissions, respectively, with distinct frequency spectra and spatial distributions. It is found that they predominate alternatively with the change of the plasma channel length. For a given plasma channel, one can switch the radiation modes by adjusting the injection position and the injection angle of the laser pulse. In particular, the radiation mode of the linear mode conversion can produce THz pulses with the peak amplitude of sub-GV cm −1 with the energy conversion efficiency ≈10 −3 , even though the peak power of the incident laser is just at the terawatt level. The scheme provides a powerful THz source with tunable intensity, spatial distributions, spectra, and polarizations by simply adjusting the injection conditions of incident laser pulses.

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Section: Two Terahertz Emission Modes From Plasma Channels With An Of...mentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Tunable High‐Field Terahertz Radiation from Plasma Channels

Wang

Chen

Zhang

et al. 2023

Laser & Photonics Reviews

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show abstract

“…Fractal antenna theory is a relatively recent field in antenna research. Fractals are patterns of self-similarity inspired by natural phenomena such as coastlines, mountains, and clouds [6][7][8]. Antenna designs can use fractals to achieve multiband resonant behavior and size miniaturization [6][7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…Fractals are patterns of self-similarity inspired by natural phenomena such as coastlines, mountains, and clouds [6][7][8]. Antenna designs can use fractals to achieve multiband resonant behavior and size miniaturization [6][7][8][9][10][11][12]. Self-similarity has been used in constructing multiband arrays and is helpful in the design of multifrequency antennas.…”

Section: Introductionmentioning

confidence: 99%

Design of Flexible Dual-Band Tree Fractal Antenna for Wearable Applications

Alkhafaji¹,

Abdulsatar²,

Ali³

2022

PIER C

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A dual-band flexible monopole antenna for wearable applications is presented. The antenna structure is built based on tree-shaped fractal geometry. The suggested antenna is printed on Rogers RT5870, a semi-flexible material with a relative dielectric constant and loss tangent of 2.33 and 0.0012, respectively. According to the results, the proposed antenna achieves dual impedance bandwidth ranging from 1.72 to 1.88 GHz for the lower band and 5.1 to 5.33 GHz for the upper band. The simulated results show that the fractional impedance bandwidths and realized gains of the antenna are 8.9/4.8% and 1.47/5.67 dBi for the 1.81/5.2 GHz, respectively. The antenna's performance under various bending scenarios has also been demonstrated at both resonant frequencies. The overall size of the proposed antenna is about 45 × 41 × 0.25 mm 3 . The antenna shows good performance to be a candidate for wearable applications.

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Analytical Framework of Small-Gap Photoconductive Dipole Antenna: An Equivalent Circuit Model

Malhotra¹,

Singh

2021

Terahertz Antenna Technology for Imaging and Sensing Applications

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Continuous terahertz wave generation based on photomixers coupled to Fibonacci fractal tree antennas

Cited by 4 publications

References 25 publications

Tunable High‐Field Terahertz Radiation from Plasma Channels

Tunable High‐Field Terahertz Radiation from Plasma Channels

Design of Flexible Dual-Band Tree Fractal Antenna for Wearable Applications

Analytical Framework of Small-Gap Photoconductive Dipole Antenna: An Equivalent Circuit Model

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