Enhanced optical-to-THz conversion efficiency of photoconductive antenna using dielectric nano-layer encapsulation

Gupta, Abhishek; Rana, Goutam; Bhattacharya, Arkabrata; Singh, Abhishek; Jain, Ravikumar; Bapat, Rudheer; Duttagupta, Siddhartha P.; Prabhu, S. S.

doi:10.1063/1.5021023

Cited by 32 publications

(20 citation statements)

References 37 publications

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“…By coating an 80 nm nano-layer of dielectric (TiO 2 ) on the active area between the electrodes of a semi-insulating GaAs-based device, shown in Fig. 11, the reflection from the Si-GaAs interface was suppressed by~6.9% [68]. In 2019, Kazemi et al used mixed graphene-gold electrodes as electrode material of the antenna, which enhanced the detected THz signal peak amplitude up to 14.31% [69].…”

Section: Optimization Of Thz Systemmentioning

confidence: 99%

“…13(a) which generate THz powers in the milliwatt range and exceed the Manley-Rowe limit for frequencies less than 2 THz [74]. In 2020, Koulouklidis et al demonstrated two-color filamentation of femtosecond mid-infrared laser pulses at 3.9 μm generating ultrashort [68] sub-cycle THz pulses with sub-milijoule energy. The results showed THz conversion efficiency of 2.36%, resulting in THz field amplitudes above 100 MV cm − 1 [75].…”

Section: Optimization Of Thz Systemmentioning

confidence: 99%

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Terahertz spectroscopy in biomedical field: a review on signal-to-noise ratio improvement

et al. 2020

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With the non-ionizing, non-invasive, high penetration, high resolution and spectral fingerprinting features of terahertz (THz) wave, THz spectroscopy has great potential for the qualitative and quantitative identification of key substances in biomedical field, such as the early diagnosis of cancer, the accurate boundary determination of pathological tissue and non-destructive detection of superficial tissue. However, biological samples usually contain various of substances (such as water, proteins, fat and fiber), resulting in the signal-to-noise ratio (SNR) for the absorption peaks of target substances are very small and then the target substances are hard to be identified. Here, we present recent works for the SNR improvement of THz signal. These works include the usage of attenuated total reflection (ATR) spectroscopy, the fabrication of sample-sensitive metamaterials, the utilization of different agents (including contrast agents, optical clearing agents and aptamers), the application of reconstruction algorithms and the optimization of THz spectroscopy system. These methods have been proven to be effective theoretically, but only few of them have been applied into actual usage. We also analyze the reasons and summarize the advantages and disadvantages of each method. At last, we present the prospective application of THz spectroscopy in biomedical field.

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Section: Optimization Of Thz Systemmentioning

confidence: 99%

Section: Optimization Of Thz Systemmentioning

confidence: 99%

Terahertz spectroscopy in biomedical field: a review on signal-to-noise ratio improvement

et al. 2020

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“…Recently, a highly electrical resistive TiO 2 was proposed as an antireflection coating in contrast to the above-mentioned materials. 105 The schematic view and an SEM image of the proposed PCA with a TiO 2 layer with its spectral characteristics are depicted in Fig. 9.…”

Section: Dielectric Metasurfacesmentioning

confidence: 99%

Metallic and dielectric metasurfaces in photoconductive terahertz devices: a review

et al. 2019

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This review highlights recent and novel trends focused on metallic (plasmonic) and dielectric metasurfaces in photoconductive terahertz (THz) devices. We demonstrate the great potential of its applications in the field of THz science and technology, nevertheless indicating some limitations and technological issues. From the state-of-the-art, the metasurfaces are, by far, able to force out previous approaches like photonic crystals and are capable of significantly increasing the performance of contemporary photoconductive devices operating at THz frequencies.

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“…4 To meet the aforementioned substrate requirements, the preferred choices for PCAs are LT-GaAs, [11][12][13] SI-GaAs, 13,14 and In-GaAs. 13,15 The suggested approaches for the enhancement of the IR coupling to PCA include antireflection coatings 16,17 and the usage of micro lens arrays. 9,11,12,16,18,19 The poor directivity issue of the PCA at room temperature is being addressed by integrating the lens shape on the back of the antenna structure 9,16,[20][21][22] and combining antenna with the metasurfaces.…”

Section: Introductionmentioning

confidence: 99%

“…13,15 The suggested approaches for the enhancement of the IR coupling to PCA include antireflection coatings 16,17 and the usage of micro lens arrays. 9,11,12,16,18,19 The poor directivity issue of the PCA at room temperature is being addressed by integrating the lens shape on the back of the antenna structure 9,16,[20][21][22] and combining antenna with the metasurfaces. 10,20 The large area emitters are also reported in literature for the reduction of saturation effects of the optical pump.…”

Section: Introductionmentioning

confidence: 99%

Full wave numerical analysis of wideband and high directive log spiralTHzphotoconductive antenna

Dhiflaoui

Yahyaoui

Yousaf

et al. 2020

Int J Numerical Modelling

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This study presents, for the first time, a novel design of ultra-wideband (UWB), circularly polarized and highly directive log-spiral THz photoconductive antenna. The proposed antenna is simulated in High Frequency Structure Simulator using gold as the antenna electrode material which is backed by a quartz substrate (ε r = 3.78, tan δ = 0.0001) and hemispherical silicon-based lens with a diameter of 140 μm. A comprehensive detailed parametric study of the antenna design parameters is performed in the frequency range of 1 to 6 THz for the optimal design of the developed antenna structure. The optimal antenna structure with integrated lens has UWB characteristics with −10 dB impedance bandwidth of 5 THz and 3 dB axial ratio bandwidth of around 4 THz. The observed directivity and half-power beam width of the presented design varies in the range 5 to 12 dBi and 34 to 62 , respectively, for the frequency range of 1 to 4 THz. The wideband, high directivity as well as highefficiency (>50%) characteristics of the proposed design make it a favorable choice for the THz sensing and imaging applications.

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Enhanced optical-to-THz conversion efficiency of photoconductive antenna using dielectric nano-layer encapsulation

Cited by 32 publications

References 37 publications

Terahertz spectroscopy in biomedical field: a review on signal-to-noise ratio improvement

Terahertz spectroscopy in biomedical field: a review on signal-to-noise ratio improvement

Metallic and dielectric metasurfaces in photoconductive terahertz devices: a review

Full wave numerical analysis of wideband and high directive log spiralTHzphotoconductive antenna

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