Average Wavelength Research Articles

Study of the surface topography and optical properties of ZnO and AZO, CZO, and CAZO thin films (in room temperature and annealed at 500 °C)

In this paper, using a sputtering technique, ZnO, and AZO, CZO, and CAZO films at room temperature (RT) were prepared and then they were annealed at 500 °C in an argon atmosphere. In as deposited films, CZO films have maximum value and for films annealed at 500 °C, CZO films have maximum value the optical density. It is found that the CAZO films have maximum value cavity obtained from the bearing area. Due to decreasing oxygen vacancies in the CAZO films, x–y fluctuations in these films have minimum value. The distributions of nanoparticles on the CAZO films annealed at 500 °C were more uniformity. The CZO films were more order. We observed that the edge absorption energy in the CAZO films annealed at 500 °C have maximum value. Average oscillator wavelength λo in the CAZO films annealed at 500 °C have minimum value of 0.09 μm.

Fiber SPR two-dimensional micro displacement sensor based on the coaxial double waveguide with a conical structure.

Fiber SPR micro displacement sensor cannot be used for two-dimensional displacement sensing at present. In this paper, we proposed and demonstrated a fiber SPR two-dimensional micro displacement sensor based on the coaxial double waveguide with a conical structure. The coaxial double waveguide is fused into a cone as the light injection fiber, and two different forms of outgoing light fields can be obtained through two cores of the fiber. The horn shaped light field emitted by the ring core of the coaxial double waveguide can cooperate with the sensing fiber to realize the micro displacement sensing in the x-axis direction. And the straight beam emitted by the middle core of the coaxial double waveguide can cooperate with the sensing fiber to realize the micro displacement sensing in the y-axis direction. Through simulation analysis and experimental test, its average wavelength sensitivity and light intensity sensitivity of the x-axis displacement are 0.0537nm/µm and 0.000124a.u./µm, respectively. And that of the y-axis displacement are 0.315nm/µm and 0.00277a.u./µm, respectively. The proposed fiber sensor realizes the two-dimensional displacement sensing based on SPR, which can be widely used in the fields of two-dimensional micro displacement measurement and two-dimensional position precision positioning.

Ultrafast Tm-doped fiber laser system delivering 1.65-mJ, sub-100-fs pulses at a 100-kHz repetition rate.

High-energy, ultrafast, short-wavelength infrared laser sources with high average power are important tools for industrial and scientific applications. Through the coherent combination of four ultrafast thulium-doped rod-type fiber amplifiers, we demonstrate a Tm-doped chirped pulse amplification system with a compressed pulse energy of 1.65 mJ and 167 W of average output power at a repetition rate of 101 kHz. The system delivers 85 fs pulses with a peak power of 15 GW. Additionally, the system presents a high long- and short-term stability. To the best of our knowledge, this is the highest average output power short wavelength IR, mJ-class source to date. This result shows the potential of coherent beam combining techniques in the short wavelength infrared spectral region for the power scalability of these systems.

Optical fiber current sensing based on a macro-bending no-core fiber structure and magnetic fluid

An all fiber current sensor based on magnetic fluid (MF) is proposed. The sensing structure is composed of a piece of no-core fiber (NCF) spliced between two sections of single mode fiber. The MF is used as the cladding of NCF. The sensing principle is based on the cladding mode interference. In order to improve the sensitivity, a bent-melt taper NCF is proposed as the sensing probe for the first time to increase the evanescent field. As a comparison, the sensitivities of optical fiber current sensors with straight NCF, bent NCF, and bent-melt taper NCF are measured in this paper. According to the experimental results, the sensitivities of optical fiber current sensor with bent-melt taper NCF are the highest among the three. The average wavelength sensitivity is 10.48 nm/A with the corresponding measurement range of 0–0.8 A, and the maximum standard deviation is 0.27 nm. The average total relative transmission loss sensitivity is 17.28 dB/A with the corresponding measurement range of 0–0.6 A, and the standard deviation of the maximum loss is 0.31 dB. The proposed sensor has good repeatability, reversibility and high sensitivity.

Nonlinear optical response, theoretical efficiencies, and high photosensitivity of CH3NH3PbI3−xClx thin films for photonic applications

In this paper, we have investigated the nonlinear optical response and theoretical efficiency of CH3NH3PbI3−xClx thin films from the optical transmission and reflection measurements. The dispersion of the complex refractive index is evaluated using the Wemple–DiDomenico single oscillator model. The oscillator energy (E0) of CH3NH3PbI3−xClx follows by an empirical relationship with optical bandgap (Eg) as E0 ≈ 2.41 Eg for chemical dip coating, spray, and E0 ≈ 1.63 Eg for dipping deposited samples, respectively. The long wavelength refractive index, average oscillator wavelength, and oscillator strength are also determined using the Sellmeier oscillator equation. The estimated third-order nonlinear optical susceptibility is found to be the order of 10−12 esu. The incident photon and charge carrier interaction in CH3NH3PbI3−xClx is studied from the dielectric response of the samples. The charge carrier excitation is found higher at lower wavelength and experienced bulk excitation in volume while surface excitation on the surface region. The optical conductivity of CH3NH3PbI3−xClx is notably high, which leads to an increase in carrier transfer through the extrinsic halide perovskite material expedient for higher conversion efficiency. The highest theoretical efficiency of CH3NH3PbI3−xClx is estimated to be 17.4%, which is in excellent agreement with the experimental report. From photosensitivity study, it is confirmed that CH3NH3PbI3−xClx films are highly photosensitive. All these results comprehend that CH3NH3PbI3−xClx is a potential candidate for photonic applications.

Research on D-Shape Open-Loop PCF Temperature Refractive Index Sensor Based on SPR Effect

PCF (Photonic crystal fiber) temperature refractive index sensor based on SPR effect with the new double membrane open-loop structure is proposed. The inner surface of such PCF&#x2019;s open-loop structure is plated with a layer of 70 nm gold film, and a layer of 20 nm SiO <inline-formula><tex-math notation="LaTeX">$_{2}$</tex-math></inline-formula> film is coated on the gold film, which could effectively prevent the gold film from oxidation corrosion. Besides, the open loop could reduce the production cost, and it could form two energy channels with nearby air holes, promoting the leakage of core energy to plasma mode and enhancing the SPR effects. The ethanol could be adopted as the temperature sensing solution, to measure the refractive index sensing of the solution to be measured. Numerical simulation is carried out based on the full vector finite element method, and the simulation results indicate that the average wavelength sensitivity of refractive index sensing could reach 3330 nm/RIU, and the wavelength sensitivity of temperature sensing could reach 0.912 nm/<inline-formula><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C, and a maximum figure of merit (FOM) of 102 which is approximately four times larger than that of the similar reported PCF-SPR sensors in the literature. The simulation results show that D-shape open-loop photonic crystal fiber has the potential application prospect on the temperature and refractive index sensing.

A High-Precision Extensometer System for Ground Displacement Measurement Using Fiber Bragg Grating

The design and performance of an innovative high-precision extensometer system, fabricated inexpensively using 3D printing technology, are discussed in this paper. In the development of the extensometer, an embedded Fiber Bragg Grating (FBG) strain sensor was 3D printed using a thermoplastic polyurethane (TPU) filament, which was used as the primary sensing element of the extensometer system, taking advantage of its excellent flexibility and high sensitivity to variations in localized strain. In the performance assessment carried out, the results obtained during the experimental test and validation have demonstrated that it could be used very effectively to measure strain variations, with an average wavelength responsivity of 0.0158 nm/cm (for displacement) and very high linearity (up to 99&#x0025;). Furthermore, the protection integrated into the sensor systems design makes it well-suited for in-the-field applications, such as monitoring ground displacements which can lead to dangerous slippages of sloped earthworks. In addition, a field testing of the extensometer under simulated conditions has shown that a Fiber Bragg Grating (FBG)-based approach could be applied effectively to the measurement of strain, offering a wavelength responsivity of 0.0012 nm/<inline-formula> <tex-math notation="LaTeX">$\mu \varepsilon $ </tex-math></inline-formula> (for strain-sensitive FBGs) under both dry and wet soil conditions. Moreover, taking advantage of the high (&#x007E;99&#x0025;) linearity, the extensometer is a reliable instrument for use in different underground conditions, creating an easy-to-use ground movement monitoring system which then enables an excellent representation of the displacement profile of the earth to be made.

High Sensitivity Surface Plasmon Resonance Sensor Based on a Ge-Doped Defect and D-Shaped Microstructured Optical Fiber.

In this work a plasmonic sensor with a D-Shaped microstructured optical fiber is proposed to detect a wide range of analyte refractive index by doping the pure silica core with distinct concentrations of Germanium Dioxide , causing the presentation of high spectral sensitivity. In this case, the fiber is shaped by polishing a coating of , on the region that will be doped with , in the polished area, a thin gold layer, which constitutes the plasmonic material, is introduced, followed by the analyte, in a way which the gold layer is deposited between the . and the analyte. The numerical results obtained in the study shows that the sensor can determine efficiently a range of 0.13 refractive index units , with a limit operation where varies from 1.32 to 1.45. Within this application, the sensor has reached an average wavelength sensitivity of up to . With this level of sensitivity, the D-Shaped format and wide range of detection, the proposed fiber has great potential for sensing applications in several areas.

Tapered Side-Polished Microfibre Sensor for High Sensitivity hCG Detection

A high sensitivity human chorionic gonado-tropin (hCG) detection was conducted by a tapered side-polished (TSP) optical fiber sensor. Experimentally, the TSP fiber sensor was made by side polishing a short section of single mode fiber to a D shape structure and tapering the D shape section to a small diameter (<inline-formula> <tex-math notation="LaTeX">$ &lt; 10~\mu \text{m}$ </tex-math></inline-formula> in the experiments). By functionalizing the primary antibody of hCG onto the TSP fiber surface, the sensor was used for detecting hCG concentration. Experimental results show that when the hCG concentration is 0.1 mIU/mL, the sensor has an average wavelength shift of 0.82 nm. The limit of detection (LoD) of the hCG is estimated 0.058 mIU/mL, assuming three times of maximum wavelength variation (<inline-formula> <tex-math notation="LaTeX">${3}\times {0}.{15}=0.45$ </tex-math></inline-formula> nm) in Phosphate buffer saline (PBS) to the measurement limit. The specificity has also been tested by immersing the sensor into a mixed biomaterial solution (hCG - 1 mIU/mL, pig-IgG - 1 <inline-formula> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula>/mL, Staphylococcus aureus <inline-formula> <tex-math notation="LaTeX">$-{6}\times {10}^{{5}}$ </tex-math></inline-formula> CFU/mL and Escherichia coli - <inline-formula> <tex-math notation="LaTeX">${2.5}\times {10}^{{5}}$ </tex-math></inline-formula> CFU/mL). The result showed that the TSP optical fiber sensor has excellent specificity. The biosensor has potential application in clinical/medical diagnostics, human health, environmental quality and food safety monitoring.

Intensive linear and nonlinear optical studies of thermally evaporated amorphous thin Cu-Ge-Se-Te films

This article is devoted to completing the study of linear and nonlinear optical characteristics of thermally evaporated a-CuxGe20-xSe40Te40, CGST, (0 ≤ x ≤ 20 at.%) thin films. The film thickness and rate of deposition were fixed in 2000 Å and 100 Å/s, respectively. Optical constants of CGST-films have been deduced from spectrophotometric measurements in the spectral range 300nm-2500 nm. The VB and CB potentials have been determined; their values increase from 0.344 eV to 0.404 eV for the CB, while increases from (-0.864 eV) to (-0.641 eV) for VB, as Cu-percentage increases. Wemple-DiDomenico single oscillator model is applied to obtain dispersion energies and parameters. The single oscillator energy decreases from 2.411 eV to 2.232 eV, while the dispersion energy increases from 14.974 eV to 20.763 eV, as Cu-ration increases. Many other important optoelectrical and dielectric parameters have also been discussed, like static refractive index, average oscillator wavelength, oscillator-length strength parameters. The surface and volume energy loss functions, optical complex conductivity (real and imaginary parts), electronic polarizability, and some nonlinear optical parameters are also well-discussed. Total electronic polarizability values increase from 4.560 Å to 3.088 Å, while the plasma frequency increases from 4.200×1014 Hz to 3.970×1014 Hz. All mapped parameters have been discussed and linked to each other, as well as studying their dependence on Cu-ratio.

A novel surface plasmon resonance-based photonic crystal fiber refractive index sensor with an ultra-wide detection range

In this paper, a novel photonic crystal fiber (PCF) refractive index (RI) sensor with an ultra-wide detection range based on the surface plasmon resonance (SPR) effect is proposed. By selectively filling the air hole with the analyte and introducing the gold-coated air hole, the high performance RI sensing can be achieved. The simulation results show that the asymmetric structure of the PCF makes the x-polarization (x-pol) and y-polarization (y-pol) core modes have different sensing characteristics. The average wavelength sensitivity of the proposed SPR-PCF RI sensor can reach − 4523 nm/RIU in the RI range from 1.25 to 1.45 for the x-pol core mode as well as − 4851 nm/RIU in the RI range from 1.25 to 1.49 for the y-pol core mode. The maximum amplitude sensitivities of − 1239.19 RIU−1 and − 1633.54 RIU−1 for the x-pol and y-pol core modes are also achieved. Moreover, the proposed SPR-PCF RI sensor can obtain the maximum resolutions of 1.603 × 10−5 and 1.695 × 10−5 RIU and figure of merits of 226.92 and 105.76 RIU−1 for the x-pol and y-pol core modes, respectively. It is believed that the proposed SPR-PCF RI sensor has potential applications in the chemistry, biology, and environment monitoring.

Double-sided polishing photonic crystal fiber biosensor based on surface plasmon resonance for cancer single cell detection

In this paper, we propose a high sensitivity double-sided polishing photonic crystal fiber biosensor based on surface plasmon resonance. The performance of the sensor was analyzed by the finite element method, including the influence of different pore sizes and positions, polishing depth, pore spacing, metal thickness, refractive index (RI), and manufacturing error (5%) on the sensing performance. And the performance of practical application in cancer detection was analyzed. The use of a double-sided polishing structure and coating with a gold layer not only increases the contact area between the analyte and gold layer but also provides a large-enough space for the analysis channel, which is conducive to the actual manufacture and use. The sensor has a detection range of 1.35–1.39, maximum wavelength sensitivity of 21,500 nm/RIU, average wavelength sensitivity of 9550 nm/RIU, amplitude sensitivity of − 1057.1756 RIU − 1 , R 2 of 0.98265, figure of merit of 250, and maximum resolution of 4.68 × 1 0 − 6 , which can be used in cancer detection and other biological areas.

Orbital forcing of late Early Devonian storm events on a mixed carbonate-siliciclastic shelf, Longmenshan area, Sichuan Province, China

AbstractThe Yangmaba Formation of latest Early Devonian age in the Longmenshan area of Sichuan Province, China, is a shelfal facies that consists of four types of carbonate-siliciclastic deposits: clay-rich, siliciclastic sand-rich, carbonate-dominated, and hybrid mixed. Storm deposits vary in their thickness, composition, and abundance-per-meter within these mixed carbonate-siliciclastic deposits. Meter-scale statistics of the relative storm frequency (events-per-meter) and magnitude (bed thickness) were compiled in two coeval sections through each of the hybrid facies in the lower Yangmaba Formation, which spans approximately the entire conodont Polygnathus patulus Zone of the uppermost Emsian Stage. Low-pass filtering, spectral analysis, and Acycle software interpretation of these tempestite statistics yield 3.5 main oscillations in each section, with an average wavelength of ~23 m. These long-wavelength trends are semi-coincident with interpreted long-term variations in sea level, where shallower depths allowed a greater influence by storms. Superimposed on the long-wavelength cycles are medium-wavelength cycles of 5.5–6.3 m. The estimated ~1.5 m.y. time-span of this conodont zone of the lower Yangmaba Formation and the approximate 1:4 ratios of these wavelengths indicate that frequency and intensity of major storms and the recording of tempestites in the sedimentary record were modulated by ~100- and 95-k.y.-short-eccentricity orbital-climate oscillations superimposed on a main 405-k.y.-long-eccentricity cycle. These eccentricity climate cycles governed storm intensity and regional sea level on this margin of the tropical Yangtze Platform of South China.

Signature of a mesospheric bore in 557.7 nm airglow emission using all-sky imager at Hanle (32.7oN, 78.9oE)

A prominent signature of dark bore front in the mesospheric O( 1 S) airglow emission is observed on a night in the late winter at Hanle (32.7 o N, 78.9 o E) located in the western Himalaya. The leading front was followed by a series of evident trailing waves and the event lasts for more than two hours. The characteristic features of the bore indicate it to be linear undular type. Instantaneous temperature profile shows presence of stable region through formation of thermal duct in the upper mesosphere possibly supported by chemistry and/or dynamics. With time, the bore fronts became faint in presence of ripples as they reached other side of imager field of view (FOV). During the initial period around 3–4 waves h −1 appear to enter the imager FOV. The observed average phase speed, period and horizontal wavelength are found to be 40 m/s, 12 min and 29 km, respectively. The bore fronts exhibit a clockwise rotation at a rate of around 5° h −1 . The front edge perpendicular to the direction of propagation shows small-amplitude undulation indicating nonuniform duct structure. The tropospheric meteorological conditions may indicate plausible contribution from jet stream, weather front (linked with the Himalayan orography), and nonmigrating tides to excite and sustain the mesospheric bore event although further investigations in this direction are being sought to understand the actual underlying physical processes.

Spatial Scales of the Velocity Shear Layer and Kelvin‐Helmholtz Waves on the Magnetopause: First Statistical Results

AbstractUsing data taken by the ARTEMIS spacecraft near Moon, we statistically study the properties of Kelvin‐Helmholtz (KH) waves and the thicknesses (ΔY) of initial velocity shear layers on the magnetopause at lunar distance. Based on a total of 48 KH wave events and 14 estimates of ΔY, the average KH wavelength (λX) and ΔY are found to be 16.05 RE and 0.53 RE at lunar distance, respectively, which are larger than those at near‐Earth magnetopause. The λX to ΔY ratio ranges from 18 to 41 at lunar distance, way beyond the range (6–13) predicted by the linear theory. This result indicates that the KH waves observed at lunar distance are not of the fastest growing mode according to linear theory. This study poses the first statistical study on λX and ΔY, providing insights into the generation and development of KH waves at lunar distance.

Strain Sensor Based on Embedded Fiber Bragg Grating in Thermoplastic Polyurethane Using the 3D Printing Technology for Improved Sensitivity

A new and easy-to-fabricate strain sensor has been developed, based on fiber Bragg grating (FBG) technology embedded into a thermoplastic polyurethane filament using a 3-dimensional (3D) printer. Taking advantage of the flexibility and elastic properties of the thermoplastic polyurethane material, the embedding of the FBG provides durable protection with enhanced flexibility and sensitivity, as compared to the use of a bare FBG. Results of an evaluation of its performance have shown that the FBG sensors embedded in this way can be applied effectively in the measurement of strain, with an average wavelength responsivity of 0.013 5 nm/cm of displacement for tensile strain and −0.014 2 nm/cm for compressive strain, both showing a linearity value of up to 99%. Furthermore, such an embedded FBG-based strain sensor has a sensitivity of ∼1.74 times greater than that of a bare FBG used for strain measurement and is well protected and suitable for in-the-field use. It is also observed that the thermoplastic polyurethane based (TPU-based) FBG strain sensor carries a sensitivity value of ∼2.05 times higher than that of the polylactic acid based (PLA-based) FBG strain sensor proving that TPU material can be made as the material of choice as a “sensing” pad for the FBG.

Opto-Mechatronics System for Train-Track Micro Deformation Sensing.

In this paper, we proposed and experimentally demonstrated an opto-mechatronics system to detect the micro-deformation of tracks caused by running trains. The fiber Bragg grating (FBG) array acting as sensing elements has a low peak reflectivity of around −40 dB. The center wavelengths were designed to alternate between 1551 nm and 1553 nm at 25 °C. Based on dual-wavelength, wavelength-division multiplexing (WDM)/time-division multiplexing (TDM) hybrid networking, we adopted optical time-domain reflectometry (OTDR) technology and a wavelength-scanning interrogation method to achieve FBG array signal demodulation. The field experimental results showed that the average wavelength shift of the FBG array caused by the passage of the lightest rail vehicle was −225 pm. Characteristics of the train-track system, such as track occupancy, train length, number of wheels, train speed, direction, and loading can be accurately obtained in real time. This opto-mechatronics system can meet the requirements of 600 mm spatial resolution, long distance, and large capacity for monitoring the train-track system. This method exhibits great potential for applications in large-scale train-track monitoring, which is meaningful for the safe operation of rail transport.

Refinement of optical/structural features and neutron/gamma-ray protecting capability of P2O5–Li2O–BaO phosphate glass system by adding Bi2O3

In this work, a new phosphate glass system with the nominal compositions 65P2O5 +10Li2O +(25-x)BaO + xBi2O3 was fabricated by using the conventional solid-state technique. Phosphate glasses were evaluated for their suitability in optical and radiation shielding applications. The amorphous nature of manufactured glasses was proved by utilizing an X-ray diffraction pattern. The density of glass samples was enhanced with rising Bi2O3 substitution ratio. UV–Vis absorption spectra were measured based on the concentration of Bi2O3 in PLBB glasses, optical energy band gap Eg for indirect and direct transitions were decreased from 3.43, 4.25 to 3.15, 3.95 eV with enhancing Bi2O3 substitution ratio respectively while urbach energy Eu was increased from 0.632 to 0.661 eV. The single oscillator energy (Eo) was found to decrease with increasing Bi2O3 however the average oscillator wavelength (λo) was increased. The Gamma-ray attenuation features of PLBB glasses were obtained via EpiXS program and MCNPX simulation codes. Mass attenuation coefficients (MAC) for PLBB0 and PLBB25 glasses were determined in the range of 14.995–0.0247 cm2/g and 43.912–0.0335 cm2/g, respectively. Outcomes obtained from MAC values and other photon shielding parameters such as MFP, HVL, Zeff, Nel, and EBF revealed that the replacement of Bi2O3 with BaO improves the capacity of PLBB glasses to reduce the intensity of gamma-rays. Furthermore, the macroscopic neutron cross section of PLBB25 glass with 25% Bi2O3 substitution is 0.133 cm−1 while it is 0.113 cm−1 for PLBB0 glass. The increase of Bi2O3 addition to the new phosphate glass system has remarkably improved both optical and nuclear radiation protecting properties.

Highly sensitive nonlinear temperature sensor based on soliton self-frequency shift technique in a microstructured optical fiber

A novel fiber-optic soliton self-frequency shift (SSFS) temperature sensor fabricated using an in-house-made microstructured optical fiber was proposed. Based on this sensor, SSFS-based sensing was systematically investigated with the variation of average pump power and pump wavelength. By detecting the central wavelength shift of the 3-dB bandwidth of the soliton with the change in temperature, the sensing performance of the proposed sensor was evaluated experimentally and theoretically, subject to the average pump power and pump wavelength. At the generation of the fundamental soliton, when the pump wavelength was fixed, the higher the average pump power, the higher the temperature sensitivity. When the average pump power was fixed, the longer the pump wavelength, the higher the temperature sensitivity. The maximum temperature sensitivity of the proposed sensor was 1.759 nm/℃ at an average pump power of 300 mW and pump wavelength of 1600 nm. This temperature sensor exhibited excellent properties, such as high sensitivity, a simple structure, an easy fabrication process, good mechanical strength, and low cost, rendering it highly applicable in fields such as food quality control, environmental monitoring, and biomedical testing.

Semitransparent Perovskite Solar Cells with Enhanced Light Utilization Efficiencies by Transferable Ag Nanogrid Electrodes

Solar cells that are semitransparent and highly efficient can find diverse applications in automobile windows, building walls, and wearable devices. Here, we present a semitransparent perovskite thin-film solar cell with an Ag nanogrid transparent electrode, where electrospun poly(ethylene oxide) (PEO) nanofibers are used as an etching mask. Directional electrospinning has allowed us to obtain a grid-shaped electrode of well-aligned Ag nanogrids. The performance of transparent electrodes can be controlled by the electrospinning conditions and the choice of substrate materials. We theoretically analyze the transmittance and sheet resistance of the electrode. Furthermore, transferable Ag nanogrid transparent electrodes are fabricated on poly(dimethylsiloxane) (PDMS) substrates for application in semitransparent perovskite solar cells. Using an electrode that shows a high transmittance (92.7%) with a low sheet resistance (18.0 Ω·sq-1), a semitransparent perovskite thin-film solar cell demonstrates average visible wavelength transmittance, power conversion efficiency, and light utilization efficiency rates as high as 25.2, 12.7, and 3.21%, respectively.