Terahertz Gas-Phase Spectroscopy Using a Sub-Wavelength Thick Ultrahigh-Q Microresonator

Vogt, Dominik Walter; Jones, Angus Harvey; Leonhardt, R.

doi:10.3390/s20103005

Cited by 19 publications

(12 citation statements)

References 49 publications

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“…[1][2][3][4] As a result, using resonators with higher quality factor and larger coupling spectrum width has been demonstrated as effect approach to improve the accuracy and range of THz sensors. [5][6][7][8][9][10][11][12] In past years, on-chip THz resonator and waveguide are widely used in the field of sensing and communication. 9,10,[13][14][15] With an increase interest in developing integrated THz devices and circuits, there is a compelling need for ultracompact on-chip THz resonators with high-quality factor and large coupling spectrum width.…”

Section: Introductionmentioning

confidence: 99%

On‐chip terahertz whispering gallery mode resonator with high‐Q based on multislot waveguide

Zhou

Xin

et al. 2023

Micro & Optical Tech Letters

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A whispering gallery mode resonator (WGMR) with a high‐quality factor and large coupling spectrum width can enhance the interaction of matter and lightwave by several orders of magnitude in a large bandwidth range. The performance of the resonator determines the accuracy and range of terahertz (THz) sensing. However, the quality factors of the reported THz WGMRs are highly limited by the high absorption loss of materials within THz spectral range. The coupling spectrum width is usually limited by the coupling structure. In this paper, an on‐chip THz whispering gallery mode resonator based on multislot waveguide and gradual coupling structure is proposed. By increasing the evanescent field of guided wave mode, the absorption loss in the resonator is significantly reduced. Through gradual coupling structure, resonance curves are more uniform within a wide spectrum. The simulation results show that the structure can improve the instinct quality factor of the THz resonator to the order of 1 0 4 $1{0}^{4}$ when the bending radius is as small as 2mm. At the same time, sensitivity is increased by more than six times and uniform resonance curves are achieved from 0.45 ~ 0.55 $0.45\unicode{x0007E}0.55$THz.

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Section: Introductionmentioning

confidence: 99%

On‐chip terahertz whispering gallery mode resonator with high‐Q based on multislot waveguide

Zhou

Xin

et al. 2023

Micro & Optical Tech Letters

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“…Such low losses give rise to ultra-narrow resonance features that imply very fine frequency selectivity. Moreover, even a slight change in the surrounding medium will perturb the resonances to a measurable extent, allowing for environmental sensitivity [ 45 ] Therefore, THz-WGMRs have been employed in relevant research works in the fields of water vapor concentration measurement [ 45 ], particle distance sensing [ 46 ], and so on. However, THz-WGMRs have not been reported on crystal water sensing.…”

Section: Introductionmentioning

confidence: 99%

Crystalline Hydrate Dehydration Sensing Based on Integrated Terahertz Whispering Gallery Mode Resonators

Hou

Yuan

Deng

et al. 2022

Sensors

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Water molecules play a very important role in the hydration and dehydration process of hydrates, which may lead to distinct physical and chemical properties, affecting their availability in practical applications. However, miniaturized, integrated sensors capable of the rapid, sensitive sensing of water molecules in the hydrate are still lacking, limiting their proliferation. Here, we realize the high-sensitivity sensing of water molecules in copper sulfate pentahydrate (CuSO4·5H2O), based on an on-chip terahertz whispering gallery mode resonator (THz-WGMR) fabricated on silicon material via CMOS-compatible technologies. An integrated THz-WGMR with a high-Q factor of 3305 and a resonance frequency of 410.497 GHz was proposed and fabricated. Then, the sensor was employed to distinguish the CuSO4·xH2O (x = 5, 3, 1). The static characterization from the CuSO4·5H2O to the copper sulfate trihydrate (CuSO4·3H2O) experienced redshifts of 0.55 GHz/μmol, whereas the dehydration process of CuSO4·3H2O to copper sulfate monohydrate (CuSO4·H2O) exhibited redshifts of 0.21 GHz/μmol. Finally, the dynamic dehydration processes of CuSO4·5H2O to CuSO4·3H2O at different temperatures were monitored. We believe that our proposed THz-WGMR sensors with highly sensitive substance identification capabilities can provide a versatile and integrated platform for studying the transformation between substances, contributing to hydrated/crystal water-assisted biochemical applications.

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“…T ERAHERTZ sensors for sophisticated applications in microfluidics, gas-phase spectroscopy, thin-film sensing, and bio-molecular sensing to name but a few are rapidly evolving [1], [2], [3], [4], [5], [6]. A common modality of these THz sensors relies on an induced resonance frequency shift upon a physical change in the system.…”

Section: Introductionmentioning

confidence: 99%

“…In particular, rapid advancements in the field of THz microresonator sensors recently culminated in the development of a sub-wavelength thin ultra-high-Q THz disc microresonator. The disc microresonator shows an unprecedented Q-factor of more than 120,000 at 0.6 THz, corresponding to an intrinsic linewidth < 5 MHz, alluding to the possibility to resolve minute resonance frequency shifts of a few megahertz [7], [3].…”

Section: Introductionmentioning

confidence: 99%

Microresonator frequency reference for terahertz precision sensing and metrology

Gandhi¹,

Leonhardt²,

Vogt³

2021

Preprint

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Highly sensitive terahertz (THz) sensors for a myriad of applications are rapidly evolving. A widespread sensor concept is based on the detection of minute resonance frequency shifts due to a targeted specimen in the sensors environment. Therefore, cutting-edge high resolution continuous wave (CW) THz spectrometers provide very powerful tools to investigate the sensors' performances. However, unpredictable yet non negligible frequency drifts common to state-of-the-art CW THz spectrometers limit the sensors' accuracy for ultra-high precision sensing and metrology. Here, we overcome this deficiency by introducing an ultra-high quality (Q) THz microresonator frequency reference. Measuring the sensor's frequency shift relative to a well-defined frequency reference eliminates the unwanted frequency drift, and fully exploits the capabilities of modern CW THz spectrometers as well as THz sensors. In a proof-ofconcept experiment, we demonstrate the accurate and repeated detection of minute resonance frequency shifts of less than 5 MHz at 0.6 THz of a THz microresonator sensor.

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Terahertz Gas-Phase Spectroscopy Using a Sub-Wavelength Thick Ultrahigh-Q Microresonator

Cited by 19 publications

References 49 publications

On‐chip terahertz whispering gallery mode resonator with high‐Q based on multislot waveguide

On‐chip terahertz whispering gallery mode resonator with high‐Q based on multislot waveguide

Crystalline Hydrate Dehydration Sensing Based on Integrated Terahertz Whispering Gallery Mode Resonators

Microresonator frequency reference for terahertz precision sensing and metrology

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