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In this paper, a racetrack ring resonator design based on a subwavelength grating double slot waveguide is presented. The proposed waveguide scheme is capable of confining the transverse electric field in the slots and the gaps between the grating segments. This configuration facilitates a large light-matter interaction which elevates the sensitivity of the device approximately 2.5 times higher than the one that can be obtained via a standard slot waveguide resonator. The best sensitivity of the design is obtained at 1000 nm/RIU by utilizing a subwavelength grating double slot waveguide of period 300 nm. The numerical study is conducted via 2D and 3D finite element methods. We believe that the proposed sensor design can play an important role in the realization of highly sensitive lab-on-chip sensors.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7349533 | PMC |
http://dx.doi.org/10.3390/s20123416 | DOI Listing |
PLoS One
September 2025
The School of Electrics and Information Engineering, Yunnan Minzu University, Kunming, China.
To address the growing demand for compact and high-performance microwave filters in modern communication systems, a mixed-mode bandpass filter is proposed in the article. A dual-layer substrate integrated waveguide resonator loaded with a capacitive patch (CP-DSIWR) is proposed and theoretically analyzed, with both patch modes and cavity modes existing. To construct the bandpass filter, two rows of metallic vias are designed in the CP-SIWR to enable coupling between the two types of the modes, with the structure being fed by microstrip line.
View Article and Find Full Text PDFSci Rep
August 2025
Institute of Applied Physics "Nello Carrara", National Research Council of Italy (CNR), Sesto Fiorentino, 50019, Italy.
Monitoring of CO is crucial because of its profound impact on both environmental and human health. A novel highly sensitive refractive index (RI) sensor, utilizing a double-slot microring resonating structure, has been designed and numerically assessed for the sensitive detection of gas media. The structure consisted of a circular microring resonator nested in a racetrack resonating configuration mimicking the structure of an eye-shaped microring resonator (ESMRR).
View Article and Find Full Text PDFSensors (Basel)
August 2025
School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer-Sheva 8410501, Israel.
The development of compact, CMOS-compatible gas sensors is critical for advancing real-time environmental monitoring and industrial diagnostics. In this study, we present a detailed numerical investigation of integrated photonic waveguide designs-such as ridge and slot-optimized for overtone-based gas spectroscopy in the near-infrared range. By evaluating both the evanescent-field confinement and curvature-induced losses across multiple silicon-on-insulator platforms, we identify optimal geometries that maximize light-analyte interactions while minimizing bending attenuation.
View Article and Find Full Text PDFSensors (Basel)
August 2025
The Department of Electrical and Computer Engineering, University of Hawaii at Manoa, Honolulu, HI 96822, USA.
This paper presents the novel design of a printed, low-cost, dual-port, and dual-polarized slot antenna for microwave biomedical radars. The butterfly shape of the radiating element, with orthogonally positioned arms, enables simultaneous radiation of both vertically and horizontally polarized waves. The antenna is intended for full-duplex in-band applications using two mutually isolated antenna ports, with the CPW port on the same side of the substrate as the slot antenna and the microstrip port positioned orthogonally on the other side of the substrate.
View Article and Find Full Text PDFIn this work, we present a design for a linear and entirely passive refractive index (RI) sensor based on silicon-on-insulator (SOI) technology, addressing the need for sensors capable of monitoring continuously changing gas concentrations. Conventional RI sensors, based on interferometers, exhibit a nonlinear response, limiting their effectiveness for applications requiring consistent performance across a wide range of refractive index changes. The proposed configuration utilizes a Michelson interferometer and two long Bragg gratings to linearize the interferometer response, ensuring a constant figure of merit (FOM) across the entire range of changes in the cover medium's refractive index.
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