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Graphene-Based Waist-Enlarged Optical Fibre Sensor for Measurement of Sucrose Concentration
摘要： A novel sucrose sensor based on graphene-coated optical fibre with waist-enlarged bitapers as Mach-Zehnder interferometer is proposed and demonstrated. The sensor is formed by arc fusion splicing a photonic crystal fibre (PCF) sandwiched between two single-mode fibres (SMFs). The intermodal interference is achieved by two waist-enlarged fibre tapers at the coupling points between the PCF and two SMFs. The result shows that the dips of transmission spectra exhibit blue shift with the concentration increase of the sucrose, and the sensor has a high linear response (R2 = 0.98233) to sucrose with an excellent sensitivity of 3.36 pm/ppm in the range of 0–230 ppm. Additionally, the surface adsorption mechanism is also discussed. Such easily fabricated, cost-effective and small volume fibre interferometer could be used for sucrose sensing applications.
关键词： Graphene,Sucrose Sensor,Blue Shift,Waist-Enlarged Bitapers,Mach-Zehnder Interferometer
更新于2025-11-28 14:23:57
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Influence of temperature and carrier density on the photoluminescence intensity of semiconductor carbon nanotubes
摘要： The role of temperature and carrier density in the photoluminescence (PL) properties of single-walled carbon nanotubes (SWNTs) is theoretically studied by solving the Bethe-Salpeter equation. Especially, the calculation of PL peak position and height for various carrier densities shows a good agreement with experimental results. The peak position and width show a moderate dependence while the intensity presents a strong dependence on temperature and density where a blue shift and intensity enhancement at low temperature are seen. These results help confirming the role of Coulomb effects on the optical transition in SWNTs.
关键词： carbon nanotube,photoluminescence,Bethe-Salpeter equation,blue shift
更新于2025-09-23 15:21:21
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Asymmetric Response Opto-Electronic Device Based on Femtosecond- Laser-Irradiated Perovskite
摘要： We have explored an asymmetric opto-electronic response of FormamidinePb(I0.8Br0.2)3 perovskite device irradiated by a femtosecond (fs) laser at different laser fluence values. Photoluminescence (PL) spectra indicated a blue shift from 772 nm (1.606 eV) to 745 nm (1.664 eV) and more than 80% quenching of the irradiated perovskite. The blue shift of the PL spectra can be attributed to compositional variation, which was confirmed through elemental analysis and X-ray diffraction. Two distinct characteristic time constants ranging from 193-46 ps and 1.9-0.61 ns were obtained by using fs transient absorption spectroscopy. The fast one represents recombination at the interface, whereas the slow one represents band-to-band recombination in the interior of the grain. Interestingly, after the perovskite was irradiated by femtosecond laser with appropriate laser fluence (0.135 J/cm2), an asymmetric I-V characteristic was achieved, which should be resulted from irreversible electric domain deflection. Due to the electron-phonon scattering induced by defect, the degree of asymmetry was sensitive to illumination power. As the photosensitive asymmetric I-V characteristics have a bearing on its photo-electric properties, the findings would be of value in photodiode, memories and other photo-electric devices.
关键词： asymmetric response,femtosecond laser,opto-electronic device,perovskite,blue shift
更新于2025-09-23 15:19:57
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Incorporation of silver ion on structural and optical characteristics of CeO2 nanoparticles: White LED applications
摘要： CeO2 and Ag incorporated CeO2 nanoparticles were prepared by the chemical co-precipitation method. The samples were analyzed by XRD, HR-TEM, FE-SEM, EDX, UV-vis, Photoluminescence, FTIR, and Photocatalytic studies. XRD results showed that Ag incorporation did not alter the structure and phase of pure CeO2 lattice. Crystallite size was reduced due to Ag ions substitution and these are good agreement with HR-TEM results. Particle size was measured as ~ 5-7 nm. EDAX and FTIR spectra confirmed the existence of elements as per the targeted stoichiometry. FE –SEM showed the surface morphology of samples and they possessed a spherical structure with surface smoothening as a function of Ag initial addition. UV- vis absorption peak intensity was increased for every increase of Ag concentration. Better optical transmittance was received for the Ag composition of 6 %. Blueshift was taken place for the incorporation of Ag ions in CeO2 host and the reason was discussed in terms of size effect and electron transition from band to band. Two peaks were received from Photoluminescence (PL) study that is one weak emission from the UV region strong emission from the red region. Red Peaks were shifted to a higher wavelength side against the addition of Ag. A fast degradation response was observed for Ag-doped CeO2 nanoparticles through photocatalytic study.
关键词： CeO2,photoluminescence,Ag,blue shift,nanoparticles
更新于2025-09-23 15:19:57
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Effect of Strontium Doping on the Band Gap of $$\hbox {CeO}_{2}$$ CeO 2 Nanoparticles Synthesized Using Facile Co-precipitation
摘要： Pure, 3 mol% and 5 mol% Sr-doped cerium oxide nanoparticles were synthesized by facile aqueous co-precipitation method using cerium nitrate hexahydrate and strontium chloride hexahydrate as the precursors without using any capping agent. The synthesized material was characterized by XRD, SEM, EDX, TEM, Raman spectroscopy and UV–Vis spectroscopic techniques. SEM analysis showed agglomeration of the particles. The Debye–Scherrer analysis revealed ?uorite structure of the synthesized material with crystallite size in 6–10 nm range. TEM con?rmed the spherical morphology of the particles and particle size distribution in the range of 5–8 nm. UV–Vis spectroscopic study revealed that Sr-doping led to increase in the band gap from 3.2 to 3.7 eV and shifting of absorption edge to the lower wavelength. The blue shift in the band gap with the dopant concentration shows that the band gap of doped cerium oxide nanoparticles can be tuned with variation in the dopant concentration.
关键词： Sr-doped cerium oxide,Blue shift,Band gap
更新于2025-09-19 17:15:36
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Propagation of circularly polarized laser in strongly magnetized over-dense collisional plasma
摘要： Permittivity of a circularly polarized (CP) laser in magnetized collisional plasma is obtained in simpli?ed form. The propagation of a CP laser in magnetized homogeneous over-dense collisional plasma was investigated, and characteristics such as attenuation length, speci?c energy deposition and blue shift are obtained. Potential applications in ?elds such as inertial con?ned fusion are discussed.
关键词： energy deposition,collisional plasma,permittivity,inertial con?ned fusion,attenuation length,blue shift,circularly polarized laser,magnetized plasma
更新于2025-09-16 10:30:52
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Thermal and electrical wavelength tuning of Bragg reflection with ultraviolet light absorbers in polymer-stabilized cholesteric liquid crystals
摘要： Autonomous stimulus-responsive polymer-stabilized cholesteric liquid crystals (PSCLCs) are promising materials for various applications. In this work, a PSCLC cell whose wavelength of selective reflection changes autonomously according to the temperature or can be controlled by applying an electric field was fabricated by using ultraviolet (UV) light absorbers. The UV light absorbers in the PSCLC cell are used not only for preventing the degradation of the substrate but also for stabilizing the polymeric network by converting the harmful UV radiation into harmless heat. To achieve the optimum conditions, different types of UV light absorbers were examined at various concentrations and UV light intensities. The results revealed that the benzophenone-type UV absorbers provide an extensive blue-shift tuning of the Bragg reflection in the PSCLC. By determining the molar extinction coefficient (e) values, which provide a measure of UV light absorption at a given wavelength, at three important wavelengths—the maximum absorption wavelength (lmax) of the UV absorbers, lmax of the photoinitiator (345 nm), and the UV lamp wavelength (365 nm)—the UV light intensity gradient throughout the cell was defined. Reduction of the e value indicates a sharp drop in the UV light intensity within a PSCLC cell. This phenomenon leads to the diffusion of reactive mesogens towards the UV lamp side of the cell to achieve a tight pitch gradient and extensive blue-shift tuning of the selective reflection.
关键词： thermal tuning,blue-shift tuning,electrical tuning,UV light absorbers,polymer-stabilized cholesteric liquid crystals
更新于2025-09-09 09:28:46