Proposal for a broadband THz refractive-index sensor based on quantum-cascade laser arrays

Zhao, Luping; Khanal, Sudeep; Wu, Chongzhao; Kumar, Sushil

doi:10.1364/oe.23.004751

Cited by 8 publications

(4 citation statements)

References 26 publications

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“…In recent years, THz sensors have been developed and used in a wide variety of fields. Zhao et al reported on a broadband THz sensor, based on quantum-cascade laser arrays, which could realize the sensing of the refractive index of solids, or liquids, in a reflective geometry [25]. Yan et al used THz fiber Bragg gratings to implement the resonant THz sensor, and it was applied to monitor the quality of paper [26].…”

Section: Introductionmentioning

confidence: 99%

Terahertz Thermal Sensing by Using a Defect-Containing Periodically Corrugated Gold Waveguide

Xue

Wang

et al. 2020

Applied Sciences

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A terahertz (THz) thermal sensor has been developed by using a periodically corrugated gold waveguide. A defect was positioned in the middle of this waveguide. The periodicities of waveguides can result in Bragg and non-Bragg gaps with identical and different transverse mode resonances, respectively. Due to the local resonance of the energy concentration in the inserted tube, a non-Bragg defect state (NBDS) was observed to arise in the non-Bragg gap. It exhibited an extremely narrow transmission peak. The numerical results showed that by using the here proposed waveguide structure, a NBDS would appear at a resonance frequency of 0.695 THz. In addition, a redshift of this frequency was observed to occur with an increase in the ambient temperature. It was also found that the maximum sensitivity can reach 11.5 MHz/K for an optimized defect radius of 0.9 times the mean value of the waveguide inner tube radius, and for a defect length of 0.2 (or 0.8) times the corrugation period. In the present simulations, a temperature modification of the Drude model was also used. By using this model, the thermal sensing could be realized with an impressive sensitivity. This THz thermal sensor is thereby very promising for applications based on high-precision temperature measurements and control.

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Section: Introductionmentioning

confidence: 99%

Terahertz Thermal Sensing by Using a Defect-Containing Periodically Corrugated Gold Waveguide

Xue

Wang

et al. 2020

Applied Sciences

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“…The THz frequency is 1-4 orders of magnitude higher than the microwaves used in 5 G. It is possible to greatly improve the information transmission rate and network capacity. In the past decade, more and more THz devices with different functions have been reported, such as filters [8][9][10][11][12], sources [13], sensors [14], slow light devices [15], switches [16], absorbers [17] and modulators [18].…”

Section: Introductionmentioning

confidence: 99%

Terahertz narrow-band filter based on 3D-printed periodic waveguides

Wang,

Liu,

et al. 2024

J. Phys. D: Appl. Phys.

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Terahertz (THz) devices, especially waveguide-type functional devices related to transmission and control, are severely scarce due to the lack of effective design and fabrication methods. Here, we experimentally demonstrate a waveguide type of THz narrow-band filter based on 3D-printed technology, which is realized by a cylindrical hollow metal structure with corrugated tube walls. The semi-cylindrical periodic corrugations are 3D printed on a photosensitive resin substrate material, followed by sputtering a layer of gold film on its surface to endow the structure with THz filtering functions. A hollow cylindrical corrugated waveguide is obtained by assembling two identical semi-circular corrugations together. The periodic structure with Bragg resonances can produce a frequency stop band, in which the propagation of THz waves is significantly suppressed. We print a wider section of corrugations in the middle of the waveguide, which destroys the perfect periodicity of the structure and forms a defect. Due to the local resonance caused by the defect, we observe an additional narrow-band transmission peak within the former stop band, which is a good candidate for THz filtering. The filtering bandwidth and extinction ratio are 1.8 GHz and 28 dB, respectively, and the Q-factor reaches 234. The proposed 3D-printed THz filter has the advantages of the simple structure, excellent performance, and easy integration, which can improve the existing THz systems in various applications.

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“…What's more, many molecules have strong rotational and vibrational absorption features at THz frequencies, leading to spectroscopic fingerprinting in the THz range [3]. Rapid developments in terahertz technologies, such as sources and detectors, have promoted various applications in sensing [4,5], non-destructive imaging [6] and spectroscopy [7]. However, water vapor and other gas molecules during transmission process could lead to severe absorptions, which limit the applications of terahertz technology.…”

Section: Introductionmentioning

confidence: 99%

Spatially, Spectrally Single-Mode and Mechanically Flexible 3D-Printed Terahertz Transmission Waveguides

Chen

Wei

et al. 2022

IEEE Photonics J.

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Emerged terahertz transmission waveguides or fibers will enable novel terahertz systems and applications. Highquality output beam profiles, mechanical flexibility and reliability are among the most crucial and challenging characteristics of terahertz transmission waveguides. Here, we design and fabricate the flexible and stretchable transmission waveguides by 3D printing to guide radiation from terahertz (THz) quantum cascade lasers (QCLs) lasing at the frequency of 2.58 THz. Composite silver nanoparticles and polydimethylsiloxane are coated on the inner surface of the 3D-printed polycarbonate/rubber substrate tube. Output beam profiles from the transmission waveguides, which are captured by a room-temperature terahertz camera, demonstrate single-mode spatial intensity distribution. Transmission spectra are measured out from the waveguides and single-mode characteristics of THz QCLs are preserved from threshold to peak bias. More than 300 times of bending and forcestrain curves are tested for the 3D-printed flexible terahertz transmission waveguides, the propagation losses exhibit no obvious change, demonstrating a superior mechanical endurance.

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Proposal for a broadband THz refractive-index sensor based on quantum-cascade laser arrays

Cited by 8 publications

References 26 publications

Terahertz Thermal Sensing by Using a Defect-Containing Periodically Corrugated Gold Waveguide

Terahertz Thermal Sensing by Using a Defect-Containing Periodically Corrugated Gold Waveguide

Terahertz narrow-band filter based on 3D-printed periodic waveguides

Spatially, Spectrally Single-Mode and Mechanically Flexible 3D-Printed Terahertz Transmission Waveguides

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