Results in Optics最新文献

Fiber optic sensors, including Fiber Bragg Grating (FBG) networks, are widely used to monitor the structural health (SHM) of infrastructure such as buildings, bridges, and tunnels. However, their multiple sensitivities make it difficult to isolate the specific impacts of each measured parameter on FBG, compromising the accuracy of the data. To overcome this challenge, we propose an innovative approach that combines FBG with the principle of Fluorescence Intensity Ratio (FIR). This combination allows for a more accurate analysis of wavelength variations in FBG, thus facilitating the distinction between temperature and deformation impacts. Additionally, we are developing a matrix formula to accurately determine temperature and deformation from FBG and FIR data, thereby improving the reliability of structural monitoring. Our results demonstrate the effectiveness of this hybrid approach through experiments and simulations, highlighting its importance in optimizing the performance of SHM devices. By integrating these two technologies, our method allows for a better understanding of parameter variations, leading to more reliable and accurate monitoring of infrastructure structural health.

The synthesis of Europium-doped Strontium based benzene dicarboxylate dimethylformamide metal–organic framework- Eu([Sr(μ-BDC)(DMF)])- with short form as Eu:SBD@MOF was carried out using the solvothermal method. The investigation involved characterization techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), CHN analysis, and energy-dispersive X-ray (EDX) elemental analysis. The results confirmed the formation of metal–organic crystals in the framework. The XRD characterization shows good alignment with the simulated pattern of SBD. The experimental absorption spectrum displays distinct transitions of the Eu (III) ion alongside transitions of the ligands. Calculations of line strengths for all observed transitions have been conducted. The Judd-Ofelt theory has been employed to determine intensity parameters, transition probabilities, branching ratios, and radiative lifetimes for the Eu: SBD@MOF. These JO parameters further aid in calculating various excited state properties. When excited by ultraviolet and visible photons, the complex exhibits emission in the red region respectively. The crystal’s dielectric loss and dielectric constant were investigated for their frequency dependence. It was observed that by virtue of DMF, a molecule linked to the crystal, a synthesized MOF exhibits a good dielectric characteristic and when the temperature is raised to 558 K, the dielectric constant drops sharply as DMF molecule could not stand after this temperature. Further ferroelectric studies reveal that the Eu: SBD@MOF has maximum polarization of 0.27 C/cm² which is greater than Rochelle salt and other MOF’s. Exploring the broadband dielectric response of metal–organic frameworks (MOFs) open up new avenues in research, potentially leading to innovative applications in smart optoelectronics, terahertz sensors, high-speed telecommunications, and microelectronics.

Body fluids carry several biomarkers and genetic material that enable the detection of carcinogenesis and tumor metastasis. Owing to this, liquid biopsy is gaining importance and entering clinical practice as an adjunct modality to the current standard of practice in cancer detection. Liquid biopsy involving specimens such as urine is non-invasive and has biomarkers reflecting the tumor microenvironment. We investigate the normal and altered levels of cellular metabolic by-products in liquid phantoms and demonstrate their photon-induced excited-state interaction behaviour for potential diagnostic applications. Short-span temporal analysis of metabolic by-products FAD and NADH in liquid phantoms with fiber optic fluorescence spectroscopy is carried out. The mixed liquid phantom of FAD and NADH, showed excited state interactions that manifested as simultaneous inverse variation in the fluorescence emission from FAD and NADH in varying pH environments. Linear discriminant analysis of the time-varying integrated fluorescence intensity resulted in a 100% accuracy in classifying liquid samples between high and low metabolite concentrations. An extension of application of the experiment model for analysis of body fluids such as urine is also discussed.

While other works use segments of nonlinear crystal to compensate for walk-off, this work utilizes a quantum dot (QD) nanostructure for such compensation. Such nanocrystal structures allow two benefits: the high nonlinear susceptibility in these nanocrystals and the high surface density of QDs in the structure. Good results are obtained for pre-chirping and modulation parameters. The results are computed at 10 and 100 kV/cm applied electric fields. Compared to ordinary nonlinear crystals, the pulse width, intensity, and efficiency of the second harmonic (SH) pulse are all higher in QD nanocrystals, even with a low electric field applied. Higher applied fields give higher results.

The use of both traffic and optical time-domain reflectometer (OTDR) in active fiber monitoring will affect the dynamic range of the OTDR due to backscattered stimulated Raman scattering (SRS). In this paper, a simulation model and hardware experiment are proposed to investigate and mitigate the effects of a backscattered SRS signal on OTDR active fiber monitoring. A basic OTDR active fiber monitoring system based on non-amplified and amplified links was developed, where the effects of SRS backscattered noise, amplification noise, and power depletion were observed. The obtained simulation results indicated that the highest backscattered SRS was contributed by the booster amplifier link configuration, where the amplification of the OTDR signal increased drastically when the signal input power reached 10 dBm. The simulation setup was also used to mitigate the backscattered SRS by placing a chirped fiber Bragg grating (CFBG) at the OTDR to allow only the 1650 nm OTDR signal to be received by the OTDR, leaving other unwanted signals or noise behind. This mitigation successfully reduced other backscattered signals by approximately 4 dB. A proof-of-concept hardware experiment was conducted to test the feasibility of the proposed technique, and the result showed that the distortion in the trace was decreased and the OTDR penalty was also reduced to 0.41 dB.

This study considered the green preparation, characterization, and investigation of the photocatalytic properties of zinc oxide magnetic nanostructure using electroplating industry effluent in the preparation. In this regard, the prepared structure was characterized by several common methods, including XRD, UV–Vis, FT-IR, DLS and VSM, and some of its properties were determined, including magnetic property, optical activity and surface charge. After determining the structure and confirming the optical activity of the prepared particles, its efficiency as a catalyst was evaluated in the photodegradation of methylene blue (MB) dye. Based on the results of the characterization of the structure of the ZnFe₂O₄ compound, the energy gap was calculated to be 3.46 eV. The results of DLS and VSM analyses showed that the prepared nanocomposite has average size, surface charge and magnetic properties equal to 65.5 nm, +95.94 mV and 8 emu/g, respectively. After confirming the photocatalytic properties of the prepared magnetic nanocomposite, the best operating conditions for the photocatalytic degradation of MB were determined to be 0.5 g of the photocatalyst, concentration of 10 mg/L of MB, pH equal to 9 and 1 mL of hydrogen peroxide (30 %) in 60 min (80 % degradation).

Light propagation in Photonic integrated circuits (PICs), which can nowadays involve complex systems of light-guiding structures, is measured with different approaches(Nuzhdin et al., 2020, Lončar et al., 2002, Hopman et al., 2007, Morichetti et al., 2014, Sapienza et al., 2012, Vesseur et al., 2007). An interferometric polarization-sensitive measurement of the evanescent fields of these structures provides insight in the performance of the circuit detects possible malfunction with sub-wavelength precision(Engelen et al., 2007, Gersen et al., 2005, Barwick et al., 2009). We demonstrate a Near-field scanning optical microscopy (NSOM) measurement on coupled ring resonators that shows how the guided modes evolve as they propagate across the optical chip. Analysis of the measurements provides information about intensity distribution of the two polarization components (TE and TM) and their spatial confinement. The data validates our methodology and opens new possibilities for analysis of signal propagation in prototyping and optimization of integrated optical systems. Direct observation of polarization state of the guided modes allows for clear understanding of mode conversion in coupling systems.

A novel humidity sensor based on a multimode graded index unclad fiber optic coated with polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) was proposed. During synthesis process, the fiber diameter underwent optical control resulting in an enhanced repeatability. The achieved sensitivity was found to be 0.219 microwatts per relative humidity percent (µW/%RH), equivalent to 0.212 dB per relative humidity (dB/RH) within a humidity range of 65–95% RH. The response time was 0.02 s per relative humidity percent (s/%RH), indicating rapid detection capabilities. Therefore, this sensor could be used for respiration monitoring. The new sensor has low hysteresis and good repeatability and linearity.

The optical properties in UV, visible and near IR spectral regions for nanocomposites based on polypropylene modified by nanoparticles of oxide compounds ZrO₂, Al₂O₃, SiO₂, MgO, TiO₂, ZnO were studied. A shift of the main optical absorption edge to the short-wave region upon modification by dielectric nanoparticles (MgO, ZrO₂, and Al₂O₃) was established. The absorption edge shifts to the long-wave region upon the introduction of semiconductor nanoparticles (ZnO, TiO₂) and amorphous SiO₂ particles. In all spectra, the absorption bands at 1200, 1400, and 1720 nm characterized by overtone vibrations of CH, CH₂, and CH₃ molecular groups were recorded. OH groups make a certain contribution to the bands at 1400 and 1720 nm. The dependence of the intensity of these absorption bands on the type and concentration of nanoparticles used in the modification of polypropylene was analyzed. X-ray diffraction analysis of the studied nanocomposites was carried out, the formation of β-PP was registered upon modification by Al₂O₃ nanoparticles. Photoluminescence spectra of nanocomposites were studied. It was found that the introduction of nanoparticles (except SiO₂) does not lead to the formation of new luminescence bands in PP.

Laser-induced fluorescence (LIF) spectroscopy of 8 essential oils (rosemary, basil, orange, lavender, peppermint, rose, pomegranate and tea tree oil) has been performed using compact blue and violet lasers operating at 447 nm and 405 nm respectively. The various features of the obtained spectra and their possible molecular origins have been discussed. Important constituents in these oils have been identified, such as two types of chlorophylls (A and B), in addition to a type of tocopherol (vitamin E). It may be possible to roughly estimate, qualitatively, the relative abundance of these constituents in these essential oils. To the best of our knowledge, the analysis of a significant number of essential oils by laser induced fluorescence (LIF) technique has not been performed before. As a future application, the technique can be used for the efficient and rapid detection adulterants in essential oils.