A waveguide-mode sensor of the spectral-readout type can be used to detect changes in the complex refractive index in the vicinity of the surface of a sensing plate by observing the change in the spectrum of light reflected on the surface. The sensor's configuration can be simplified by adopting a parallel-incidence-type optical setup. To obtain a high sensitivity, the optimization of the sensing-plate structure, incidence angle, and detection wavelength band is essential for the sensor. In the present report, the results predicted by simulations are compared with experimental results in order to evaluate their validity. A discussion of the optimal design for the parallel-incidence-type sensor is also presented, according to the results obtained.
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http://dx.doi.org/10.1364/OE.23.010925 | DOI Listing |
Sci Rep
January 2025
Terahertz Research Center, School of Electronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu, 610054, China.
Strong light-matter coupling occurs when the rate of energy exchange between the electromagnetic mode and the molecular ensemble exceeds the competitive dissipation process. Coupled photon molecules with near-field light-matter interactions may produce new hybridized states when they reach the strong coupling region. Tunable Terahertz (THz) meta materials can be used to design sensors, optical modulators, etc.
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December 2024
School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
We observed tunable characteristics of optical frequency combs (OFCs) generated from InGaAs/GaAs double quantum wells (DQWs) asymmetric waveguide two-section mode-locked lasers (TS-MLLs). This involves an asymmetric waveguide mode-locked semiconductor laser (AWML-SL) operating at a center wavelength of net modal gain of approximately 1.06 µm, which indicates a stable pulse shape, with the power-current(P-I) characteristic curve revealing a small difference between forward and reverse drive currents in the gain region.
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June 2023
Institute of Materials Research and Engineering, Agency for Science, Technology and Research, Innovis, Singapore 138634 Singapore.
We present a general optimization technique for surface plasmon resonance, (SPR) yielding a range of ultrasensitive SPR sensors from a materials database with an enhancement of ∼100%. Applying the algorithm, we propose and demonstrate a novel dual-mode SPR structure coupling SPP and a waveguide mode within GeO featuring an anticrossing behavior and an unprecedented sensitivity of 1364 deg/RIU. An SPR sensor operating at wavelengths of 633 nm having a bimetal Al/Ag structure sandwiched between hBN can achieve a sensitivity of 578 deg/RIU.
View Article and Find Full Text PDFNat Nanotechnol
December 2022
Blackett Laboratory, Imperial College London, London, UK.
The Raman scattering of light by molecular vibrations is a powerful technique to fingerprint molecules through their internal bonds and symmetries. Since Raman scattering is weak, methods to enhance, direct and harness it are highly desirable, and this has been achieved using optical cavities, waveguides and surface-enhanced Raman scattering (SERS). Although SERS offers dramatic enhancements by localizing light within vanishingly small hot-spots in metallic nanostructures, these tiny interaction volumes are only sensitive to a few molecules, yielding weak signals.
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August 2022
Graduate Faculty of Interdisciplinary Research, University of Yamanashi, Kofu 400-8510, Japan.
Humidity measurement is required in various fields. We previously developed a sensor that leverages the sudden change in the transmitted light intensity when switching from leakage mode to waveguide mode. By adjusting the low-refractive-index polymer of the cladding, we achieved measurements at 60% RH.
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