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Enhancing the Speed and Sensitivity of a Nonlinear Optical Sensor with Noise
摘要： We demonstrate how noise can be turned into a resource for optical sensing using a nonlinear cavity. The cavity is driven by a continuous-wave laser into the regime of optical bistability. Due to the influence of fluctuations, the cavity switches randomly between two metastable states. By analyzing the residence times in these two states, perturbations to the resonance frequency of the cavity can be detected. Here, such an analysis is presented as a function of the strength of the perturbation and of the noise. By increasing the standard deviation of the noise, we find that the detection speed increases monotonically while the sensitivity peaks at a finite value of the noise strength. Furthermore, we discuss how noise-assisted sensing can be optimized in state-of-the-art experimental platforms, relying solely on the minimum amount of noise present in the cavity due to its dissipation. These results open up new perspectives for the ultrafast detection of nanoparticles, contaminants, gases, or other perturbations to the resonance frequency of an optical resonator, at low powers and in noisy environments.
关键词： noise,residence times,nonlinear optical sensor,sensitivity,optical bistability,detection speed
更新于2025-09-23 15:19:57
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Optical fiber surrounded by a graphene layer as an optical sensor
摘要： An optical sensor composed of a circular cylindrical fiber surrounded by graphene layer is investigated. The thin layer of graphene is located at the core–cladding interface. The cladding is an aqueous material. The conductivity ( ?? ) of the graphene layer is taken as ?? = ??? + j???? is the real and imaginary parts of the conductivity. We consider TE waves to propagate in the structure. Using Maxwell’s equations, the dispersion relation is derived. Also, the sensitivity of the effective refractive index to any changes in the aqueous cladding refractive index is deduced. It is found that the sensitivity of the proposed optical fiber can be dramatically improved with the variation of graphene layer conductivity.
关键词： Optical sensor,Optical fiber,Graphene,Sensitivity
更新于2025-09-23 15:19:57
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Encapsulation of Dual Emitting Giant Quantum Dots in Silica Nanoparticles for Optical Ratiometric Temperature Nanosensors
摘要： Accurate temperature measurements with a high spatial resolution for application in the biomedical fields demand novel nanosized thermometers with new advanced properties. Here, a water dispersible ratiometric temperature sensor is fabricated by encapsulating in silica nanoparticles, organic capped PbS@CdS@CdS “giant” quantum dots (GQDs), characterized by dual emission in the visible and near infrared spectral range, already assessed as efficient fluorescent nanothermometers. The chemical stability, easy surface functionalization, limited toxicity and transparency of the silica coating represent advantageous features for the realization of a nanoscale heterostructure suitable for temperature sensing. However, the strong dependence of the optical properties on the morphology of the final core–shell nanoparticle requires an accurate control of the encapsulation process. We carried out a systematic investigation of the synthetic conditions to achieve, by the microemulsion method, uniform and single core silica coated GQD (GQD@SiO2) nanoparticles and subsequently recorded temperature-dependent fluorescent spectra in the 281-313 K temperature range, suited for biological systems. The ratiometric response—the ratio between the two integrated PbS and CdS emission bands—is found to monotonically decrease with the temperature, showing a sensitivity comparable to bare GQDs, and thus confirming the effectiveness of the functionalization strategy and the potential of GQD@SiO2 in future biomedical applications.
关键词： silica shell,QD functionalization,nanothermometers,optical sensor,ratiometric sensing
更新于2025-09-23 15:19:57
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Plasmonic biosensors fabricated by galvanic displacement reactions for monitoring biomolecular interactions in real time
摘要： Optical sensors are prepared by reduction of gold ions using freshly etched hydride-terminated porous silicon, and their ability to specifically detect binding between protein A/rabbit IgG and asialofetuin/Erythrina cristagalli lectin is studied. The fabrication process is simple, fast, and reproducible, and does not require complicated lab equipment. The resulting nanostructured gold layer on silicon shows an optical response in the visible range based on the excitation of localized surface plasmon resonance. Variations in the refractive index of the surrounding medium result in a color change of the sensor which can be observed by the naked eye. By monitoring the spectral position of the localized surface plasmon resonance using reflectance spectroscopy, a bulk sensitivity of 296 nm ± 3 nm/RIU is determined. Furthermore, selectivity to target analytes is conferred to the sensor through functionalization of its surface with appropriate capture probes. For this purpose, biomolecules are deposited either by physical adsorption or by covalent coupling. Both strategies are successfully tested, i.e., the optical response of the sensor is dependent on the concentration of respective target analyte in the solution facilitating the determination of equilibrium dissociation constants for protein A/rabbit IgG as well as asialofetuin/Erythrina cristagalli lectin which are in accordance with reported values in literature. These results demonstrate the potential of the developed optical sensor for cost-efficient biosensor applications.
关键词： Surface functionalization,Optical sensor,Lectin,Localized surface plasmon resonance,Biomolecular interactions,Gold nanostructure
更新于2025-09-23 15:19:57
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The International Round Robin Test of Magnetostriction Measurement of Grain-oriented Electrical Steel by Means of a Single Sheet Tester and an Optical Sensor
摘要： This paper reports the results of the round robin test (hereafter RRT) of magnetostriction measurement using the test apparatus following IEC 60404-17 from April 2019 to August 2019. The main purpose of the RRT is to identify factors affecting the magnetostriction measurement, and then to estimate the reproducibility of the measurements. Nine anonymous laboratories, whose test apparatuses are a little different from the draft standard, participated in the RRT. In the progress of the RRT, we identified factors affecting the magnetostriction measurement. Finally, the reproducibility of the measurements was estimated. Doshisha Univ. acts as the reference laboratory.
关键词： Single Sheet Tester,Optical Sensor,Magnetostriction,Grain-oriented Electrical Steel,Round Robin Test
更新于2025-09-23 15:19:57
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Impact of Pulse Width on the Sensitivity and Range of a Raman-based Distributed Fiberoptic Temperature Sensor
摘要： This work presents the operation of a spontaneous Raman scattering-based distributed fiber-optic temperature sensor using a commercial OTDR and a standard EDFA optical amplification in a simple and economic scheme. We present both theoretical and experimental results regarding the sensor’s sensitivity and performance in seven different configurations, using OTDR pulses of 100 ns to 4000 ns for two detection regions, in the beginning and ending sections of a 27 km standard single-mode fiber sensor link. The results reveal the trade-off between sensor sensitivity, resolution and range, regarding the use of different OTDR pulsewidths.
关键词： Raman Scattering,optical sensor,Optical Fiber,OTDR,temperature sensor
更新于2025-09-19 17:15:36
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Design of Chalcopyrite-type CuFeSe2 Nanocrystals: Microstructure, Magnetism, Photoluminescence and Sensing performances
摘要： Most of reported I-III-VI2 type chalcopyrites have been developed as indispensible materials for potential application in photovoltaic solar cells, magnetism or thermoeletrics. The exploration of its photoluminescence potentials has been very limited and the chemical sensing using fluorescence to signal a recognition event is realized by way of CuFeSe2 nanocrystals. A novel solution-based synthesis strategy has been developed for the preparation of CuFeSe2 quantum dots (QDs) via oleylamine and dodecanethiol as precursors. QDs possess an intense blue luminescence at 431 nm and excitation-dependent features are recorded. The nanocrystals exhibit transformation from ferromagnetism to paramagnetism state between 4K and 298K. Another distinct advantage of the quantum dots will be the signaling pathway in response to external analytes. It gives rise to a rapid and selective assay of Cr2O7 2- through an “on-off” switching process. A linear equation can be obtained in the range from 0 to 47.5 μM and the detection limit has been determined to be 0.46 μM. This cost-effective method will pave the way for the efficient synthesis of ternary chalcopyrites and provide suitable chemical routes for sensing purposes.
关键词： Optical sensor,Nanocrystals,Magnetic,CuFeSe2
更新于2025-09-19 17:15:36
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Aryl triazene derivative immobilized on agarose membrane for selective optical sensing and quantitation of Ni2+ in water
摘要： An aryl triazene (3-hydroxy-3-phenyl triaz-1-en-1-benzoic acid) was synthesized and first utilized as a highly selective ligand for the preparation of a novel optical sensor for nickel ion determination in aqueous solutions. The ligand was chemically bonded to a transparent agarose membrane after its epoxy activation for this purpose. Study of the complex formation between the ligand and some metal ions including Ni2+, Cu2+, UO2 2+, Cr3+, Fe3+, Mg2+, Co2+, Pb2+, Ca2+, and Ag+, in aqueous media, indicated a high selectivity towards Ni2+ and Cu2+ for it. After immobilization of the ligand on the agarose membrane, its selectivity for Ni2+ was substantially increased and a more distinct isosbestic point was observed. In addition, a sharp color change from yellow to green was detected upon contact with a solution of nickel ion at pH 9. The effects of pH, ligand concentration, response time, and interfering ions were carefully studied for the optical sensor. No significant interference from the above metal ions was observed. The absorbance of the membrane at 420 nm was linear for Ni2+ concentrations up to 9 × 10?4 mol L?1 with an R2 of 0.991. A detection limit of 2.74 × 10?6 mol L?1, repeatability of 2.2%, and reproducibility of 4.2% were obtained for the Ni2+ quantitation. The optical sensor was used for the analysis of nickel ion in some river water samples with satisfactory results.
关键词： Agarose membrane,Aryl triazene,Nickel ion,Optical sensor
更新于2025-09-19 17:15:36
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Large Wavelength Response to Pressure Enabled in InGaN/GaN Microcrystal LEDs with 3D Architectures
摘要： Optical detection of pressure has the advantage of direct and dynamic indication of the pressure distribution with a high spatial resolution. In this study, microcrystal (μ-crystal) light-emitting diodes (LEDs) that can exhibit an unprecedented large wavelength response to pressure are demonstrated. As a key strategy, three-dimensional InGaN/GaN μ-crystals are engineered to have a hollow core and multiple facets with different multiple quantum well (MQW) structures. The unique structure allows pressure-sensitive modulation of the dominantly emitting MQWs, resulting in an anomalously large change of ~50 nm in the ultimate emission wavelength under an external stress of 8 MPa. The underlying mechanism is elucidated via finite-element analysis of the strain development in the μ-crystals and the corresponding piezo-potentials. The results of the study suggest a new capability for dynamic color mapping of the pressure distribution with a high spatial resolution.
关键词： InGaN/GaN microcrystal,micro-LED,optical sensor,wavelength change,pressure sensor
更新于2025-09-19 17:13:59
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A 3D net-like structured fluorescent aerogel based on carboxy-methylated cellulose nanofibrils and carbon dots for a highly effective adsorbent and sensitive optical sensor of Cr(VI)
摘要： To effectively detect and remove Cr(VI) from aqueous solution, a 3D net-like structured fluorescent aerogel was designed and synthesized using highly photoluminescent carbon dots (CDs) and renewable natural carboxy-methylated cellulose nanofibrils (CM-CNF). The surface morphology, microstructure, chemical elements and fluorescence properties of this novel aerogel were studied. Sorption experiments were designed to investigate the sorption properties of Cr(VI) onto this fluorescent aerogel. The adsorption process was described by pseudo-second-order kinetic model and Freundlich model, and the maximum adsorption capacity for Cr(VI) reached 433.5 mg g–1. Furthermore, this novel aerogel emitted bright blue fluorescence with a quantum yield of 11.8 % when applied to Cr(VI) sensing, and a good linear relationship between the quantum yield and Cr(VI) concentration was demonstrated. Accordingly, this novel 3D net-like structured fluorescent aerogel should be a promising smart sorbent for the removal of Cr(VI) with advantages of the 3D net-like structure and rich functional groups that accelerate Cr(VI) sorption and the wrapped fluorescent probe that improves Cr(VI) sensing.
关键词： optical sensor,Cr(VI) removal,3D net-like structured fluorescent aerogel,carboxy-methylated cellulose nanofibrils,carbon dots
更新于2025-09-19 17:13:59