Terahertz Spiral Spatial Filtering Imaging

Liu, Hui; Wu, Shiyou; Zhao, Meng; Li, Chao; Liu, Xiaojun; Fang, Guangyou

doi:10.3390/app11062526

Cited by 3 publications

(3 citation statements)

References 36 publications

(38 reference statements)

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“…Indeed, there has been a lot of work to manipulate the THz radiation in free space using metamaterial-based filters, which are crucial to enhance efficiency in applications such as astronomy, THz signal processing, imaging, and data communication. [24,[35][36][37][38] However, to significantly reduce THz system sizes, efforts need to be made to develop topological on-chip filters for T 2 PIC devices.…”

Section: Introductionmentioning

confidence: 99%

Electrically Tunable Topological Notch Filter for THz Integrated Photonics

Gupta,

Kumar,

Singh

2023

Advanced Optical Materials

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Electromagnetic filtering is essential for emerging integrated photonic technologies and widely adaptable processing of high‐bandwidth signals. The conventional electro‐optic modulator‐based photonic approach for signal filtering at microwave frequencies cannot be implemented at terahertz (THz) frequencies due to the unavailability of the THz signal‐driven optical modulator. Here, an electrically tunable on‐chip THz photonic notch filter based on the topologically protected valley hall waveguide‐cavity platform is demonstrated. The device shows a significantly large notch suppression depth of more than 20 dB with a return loss of 13 dB in the entire tuning range of notch frequency. The feedback control circuit enables precise control of the notch frequency shift with a minimum step size of 7 MHz. This work extends the application of topological photonic crystals in developing THz‐integrated photonic devices for transformative technologies, including sixth‐generation (6G) communication and high‐resolution spectral sensing.

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Section: Introductionmentioning

confidence: 99%

Electrically Tunable Topological Notch Filter for THz Integrated Photonics

Gupta,

Kumar,

Singh

2023

Advanced Optical Materials

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“…However, due to various challenges, such as material absorption in this spectral region, creating broadband optical elements is not straightforward, and innovative beam-shaping methods have been investigated. For example, enhanced contrast and edge detection of THz imaging were recently achieved using spiral spatial filtering; nondiffracting THz Bessel waves were realized and demonstrated improved image resolution and a spatiotemporal coupling with an X-shape profile; , and single-cycle THz vortex beams were generated and used to investigate nonlinear absorption in bilayer graphene . In addition, THz pulsed time domain holography (THz-PTDH), a technique for high resolution imaging of THz amplitude and phase, has been introduced and explored, − allowing mapping of spectroscopic information in the imaged object.…”

Section: Introductionmentioning

confidence: 99%

Generating Angular-Varying Time Delays of THz Pulses via Direct Space-to-Time Mapping of Metasurface Structures

Elias,

Sideris,

McDonnell

et al. 2023

ACS Appl. Opt. Mater.

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We experimentally demonstrate the generation of double terahertz (THz) pulses with tailored angular-dependent time delays from a nonlinear metasurface excited by a near-infrared femtosecond pulse. The tailored temporal properties of the generated pulses emerge from a direct mapping of the nonlinear spatial response of the metasurface to the emitted THz temporal profile. We utilize the Pancharatnam-Berry phase to implement symmetric and antisymmetric metasurface configurations and show that the emitted patterns present spatiotemporal “X-shaped” profiles after collimation by a parabolic mirror, with angular-dependent pulse delays corresponding to the intended design. In addition, we show that the addition of polarization multiplexing presents the opportunity to achieve a full range of elliptical THz polarizations. Double pulse generation and spatiotemporal shaping of THz waves in general show potential for THz spectroscopy and molecular dynamics applications, particularly in pump–probe experiments.

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“…Compared to the microwave band, it can achieve a higher imaging resolution [1,2]. Due to the above advantages, the THz imaging systems have attracted extensive attention in the field of security inspection, non-destructive testing (NDT) and other applications [3,4].…”

Section: Introductionmentioning

confidence: 99%

A THz Passive Image Generation Method Based on Generative Adversarial Networks

Yang

Liu

et al. 2022

Applied Sciences

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A terahertz (THz) passive imager with automatic target detection is an effective solution in the field of security inspection. The high-quality training datasets always play a key role in the high-precision target detection applications. However, due to the difficulty of passive image data acquisition and the lack of public dataset resources, the high-quality training datasets are often insufficient. The generative adversarial network (GAN) is an effective method for data augmentation. To enrich the dataset with the generated images, it is necessary to ensure that the generated images have high quality, good diversity, and correct category information. In this paper, a GAN-based generation model is proposed to generate terahertz passive images. By applying different residual connection structures in the generator and discriminator, the models have strong feature extracting ability. Additionally, the Wasserstein loss function with gradient penalty is used to maintain training stability. The self-developed 0.2 THz band passive imager is used to carry out imaging experiments, and the imaging results are collected as a dataset to verify the proposed method. Finally, a quality evaluation method suitable for THz passive image generation task is proposed, and classification tests are performed on the generated images. The results show that the proposed method can provide high-quality images as supplementary.

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Terahertz Spiral Spatial Filtering Imaging

Cited by 3 publications

References 36 publications

Electrically Tunable Topological Notch Filter for THz Integrated Photonics

Electrically Tunable Topological Notch Filter for THz Integrated Photonics

Generating Angular-Varying Time Delays of THz Pulses via Direct Space-to-Time Mapping of Metasurface Structures

A THz Passive Image Generation Method Based on Generative Adversarial Networks

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