Effects of surface roughness on terahertz transmission spectra

Yang, Yu; Zhang, Zhaohui; Zhang, Tianyao; Zhao, Xingke; Chen, Yan; Cao, Can; Liu, Ying; Xu, Kun

doi:10.1007/s11082-020-02365-x

Cited by 7 publications

(1 citation statement)

References 24 publications

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“…In 2004, Technology Review's editors selected THz technology as one of "10 emerging technologies that will change your world" [3]. THz technology is used in the following fields: medicine [4,5], biology [6], security [7], non-destructive evaluation [8], agriculture [9], telecommunication [10], pharmaceutical [11], spectroscopy [12,13], cultural heritage [14], etc. The abovementioned applications show that the THz technology is an interdisciplinary technology.…”

Section: Introductionmentioning

confidence: 99%

Wave Propagation in an Optimized Tunable Multi-channel Flter based on One-dimensional Nano Superconductor Photonic Crystal

Baseri

Keshavarz

2021

Preprint

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Although there has been a focus on THz lters so far, there is a signifcant defciency in advancing low-temperature THz lters. According to the needs, we proposed a tunable THz lter that selectively permits the desired incident frequencies to be propagated in relevance with our purpose. The presence of a low-temperature nano superconductor and an undoped semiconductor layers in the proposed structure resulted in a multi-channel THz lter, which could be highly tuned with several parameters such as lattice constants, applied temperature, etc. The achieved transmittance spectra revealed that the emerged transmittance couples and stacks follow exact regulations. Furthermore, the structure exhibited omnidirectional band-gaps for both TE and TM polarized waves. Moreover, the use of a central defect layer gave some transmittance defect modes in the forbidden areas. This structure could be used in some THz devices such as switches, optimized sensors as well as in space industry and telecommunications.

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Section: Introductionmentioning

confidence: 99%

Wave Propagation in an Optimized Tunable Multi-channel Flter based on One-dimensional Nano Superconductor Photonic Crystal

Baseri

Keshavarz

2021

Preprint

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A recurrent neural network for adaptive filtering in terahertz time-domain spectroscopy

Qiu,

Wang,

et al. 2024

Infrared Physics & Technology

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Non-contact, portable, and stand-off infrared thermal imager for security scanning applications

Khor,

Chen,

Roberts

et al. 2024

AIP Advances

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In this article, we demonstrated the physical application of a portable infrared (IR) security scanning system for the non-contact and stand-off detection of target objects concealed underneath clothing. Such a system combines IR imaging and transfer learning with convolutional neural networks (CNNs) to enhance the detection of weak thermal signals and automate the classification of IR images. A mid-wavelength IR detector was used to record the real-time heat emitted from the clothing surface by human subjects. Concealed objects reduce the transmissivity of IR radiation from the body to the clothing surface, generally showing lower IR intensity compared to regions without objects. Due to limited resources for training data, the transfer learning approach was applied by fine-tuning a pre-trained CNN ResNet-50 model using the ImageNet database. Two image types were investigated here, i.e., raw thermal and Fuzzy-c clustered images. Receiver operating characteristic curves were built using a holdout set, showing an area-under-the-curve of 0.8934 and 0.9681 for the raw and Fuzzy-c clustered image models, respectively. The gradient-weighted class activation mapping visualization method was used to improve target identification, showing an accurate prediction of the object area. It was also found that complex clothing, such as those composed of materials of different transmissivity, could mislead the model in classification. The proposed IR-based detector has shown potential as a non-contact, stand-off security scanning system that can be deployed in diverse locations and ensure the safety of civilians.

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Effects of surface roughness on terahertz transmission spectra

Cited by 7 publications

References 24 publications

Wave Propagation in an Optimized Tunable Multi-channel Flter based on One-dimensional Nano Superconductor Photonic Crystal

Wave Propagation in an Optimized Tunable Multi-channel Flter based on One-dimensional Nano Superconductor Photonic Crystal

A recurrent neural network for adaptive filtering in terahertz time-domain spectroscopy

Non-contact, portable, and stand-off infrared thermal imager for security scanning applications

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