We demonstrate a significant reduction in the limit of label-free detection of individual viral-sized nanoparticles in aqueous solution through the use of a frequency doubled telecom laser constructed from a distributed feedback-periodically poled lithium-niobate (DFB-PPLN) union. By driving a whispering gallery mode biosensor near a wavelength of 650 nm with this device we have detected real-time adsorption steps for particles 36 nm in radius with a signal to noise ratio of 8. The noise equivalent detection limit is ∼20 ag (17 nm radius). This new lower limit is attributed to the ultralow resonance wavelength noise [(Δλ(r))(rms)/λ(r)<10(-9)] associated with the use of the DFB-PPLN device.
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http://dx.doi.org/10.1063/1.3499261 | DOI Listing |
A novel, to the best of our knowledge, optical fiber whispering-gallery mode (WGM) sensor for simultaneously measuring humidity and temperature is proposed and investigated. The proposed sensor is realized by a polyvinyl alcohol (PVA)-coated capillary tube coupling with an optical single-mode fiber (SMF), which is integrated with a fiber Bragg grating (FBG). The as-fabricated sensor can be used not only for relative humidity (RH) sensing but also for temperature detection.
View Article and Find Full Text PDFNat Protoc
January 2025
Wyant College of Optical Sciences, The University of Arizona, Tucson, AZ, USA.
Sensitive, rapid and label-free biochemical sensors are needed for many applications. In this protocol, we describe biochemical detection using FLOWER (frequency locked optical whispering evanescent resonator)-a technique that we have used to detect single protein molecules in aqueous solution as well as exosomes, ribosomes and low part-per-trillion concentrations of volatile organic compounds. Whispering gallery mode microtoroid resonators confine light for extended time periods (hundreds of nanoseconds).
View Article and Find Full Text PDFLight Sci Appl
January 2025
State Key Laboratory of Luminescent Materials and Devices, and Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, School of Materials Science and Engineering, South China University of Technology, 510640, Guangzhou, China.
Visible light microlasers are essential building blocks for integrated photonics. However, achieving low-threshold (μW), continuous-wave (CW) visible light lasing at room temperature (RT) has been a challenge because of the formidable requirement of population inversion at short wavelengths. Rare-earth (RE)-activated microcavities, featuring high-quality factor (Q) and small mode volume of whispering gallery modes, offer a great opportunity for achieving infrared-to-visible upconversion (UC) lasing.
View Article and Find Full Text PDFACS Appl Mater Interfaces
January 2025
Fujian Provincial Key Laboratory of Polymer Materials, College of Chemistry and Materials Science, Fujian Normal University, Fuzhou 350007, China.
Luminescent metal-organic frameworks (MOFs) with exceptional dynamics and diverse active sites possess tremendous potential in information security and anticounterfeiting applications. However, traditional MOF systems are based on broadband spectral signals with spectrum overlap, which easily leads to low-resolution signal identification, compromising the overall security level. Here, we report the coordination-defect-induced amorphous pure-MOF microsphere with switchable whispering-gallery-mode (WGM) signals as a mode-dependent security platform.
View Article and Find Full Text PDFACS Photonics
December 2024
Graduate School and Faculty of Information Science and Electrical Engineering, Kyushu University, 744 Motooka Nishi-ku, Fukuoka, 819-0395, Japan.
Whispering-gallery mode (WGM) resonators, renowned for their high Q-factors and narrow line widths, are widely utilized in integrated photonics. Integrating diffraction gratings onto WGM cavities has gained significant attention because these gratings function as azimuthal refractive index modulators, enabling single-mode WGM emissions and supporting beams with orbital angular momentum (OAM). The introduction of curved grating structures facilitates guided mode resonances by coupling high-order diffracted waves with leaking modes from the waveguide.
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