Optical Transmission Loss Research Articles

Modeling and Optimization of Laser Cladding Fixation Process for Optical Fiber Sensors in Harsh Environments.

In order to overcome the shortcomings of the poor shear resistance of the bare optical fiber whose coating layer falls off due to harsh conditions, such as on aero-engines and the marine environment, the coaxial powder feeding laser cladding method (CPFLCM) is proposed to connect the optical fiber sensor and the substrate. The concentration field model of the powder flow is established in sections, the effective number model of particles and the corresponding laser attenuation rate are obtained. Through simulation, the influence of relevant parameters of laser cladding on the temperature field was analyzed, and the accurate parameters of laser cladding were optimized. Finally, the temperature rise trajectory of the substrate temperature field was verified by using the fiber grating temperature sensor. Through experiments, the quality of the molten pool and the optical transmission loss of the optical fiber sensor were analyzed, and the consistency of the simulation optimization parameters was verified. Through this paper, it can be concluded that the proposed CPFLCM can realize the effective connection of the optical fiber sensor to the substrate. It is of great significance in the application of optical fiber sensors in harsh environments of oceans and aerospace.

Optical characterization and polaron radius of Bi2O3 doped silica borotellurite glasses

A system of silica borotellurite glasses containing bismuth oxide (Bi2O3) with empirical chemical relation [{(TeO2)0.7(B2O3)0.3}0.8(SiO2)0.2]1−x(Bi2O3)x (where x = 0.01–0.05 M fraction in step of 0.01) were synthesized via melt-quenching procedure. Density and molar volume, XRD, FTIR and UV–Vis spectroscopies were employed to examine some parameters related to physical, structural and optical properties of the glasses. The density, polaron radius, molar volume, oxygen packing density (OPD), oxygen molar volume and number of bonds per unit volume of the glasses were computed and discussed. The XRD and FTIR characterization results were presented and discussed accordingly. Via the obtained optical absorption and density/molar volume data, the band gap energy, Urbach energy, index of refraction, coefficient of optical transmission, metallization criterion (MC) and reflection loss were studied. The index of refraction, metallization criterion, coefficient of optical transmission and reflection loss range from 3.013 to 2.622, 0.271–0.338, 0.598–0.667 and 0.252–0.201 respectively. The values of Polaron radius range from 3.949 to 4.300 g cm−3, 73.009–72.297 g atm l−1 and 6.943–4.092 Å respectively. The obtained values of the polaron radius are termed small polarons because they are within the lattice constants of each of the constituent oxides in the BSBT glasses. The MC values of the glasses are consistent with MC of non-metallic glasses as well as new nonlinear optical materials. High values of density, index of refraction and the value range of the metallization criterion suggest that the TeO2–B2O3–SiO2–Bi2O3 glasses are suitable for optoelectronic, nonlinear optical devices and radiation attenuation windows.

High-temperature recrystallization effects in swift heavy ion irradiated KY(WO4)2

KY(WO4)2 crystal has a lot of potential as an on-chip waveguide material for lanthanide ion-doped, Raman active lasers and on-chip amplifiers. One method of fabricating these waveguides is by using swift carbon ion irradiation, which produces a step-like, damage-induced refractive index contrast of up to Δn≈0.2. The irradiation is followed by an annealing step to reduce color centers that cause high optical absorption, leading to an optical slab waveguide with optical transmission losses as low as 1.5 dB/cm at 1550 nm. In this article, we report an upper limit of ∼450°C to the annealing temperature, above which stresses and recrystallization induce additional scattering detrimental to waveguide performance. The effects are characterized using transmission electron microscopy and Raman microscopy.

Optical Transmission Losses of a TiO2-based Anti-soiling Coating for Use in Outdoor Photovoltaic Applications

Background: Soiling can be a major challenge for photovoltaic (PV) installations, depending on their location, as it reduces transmission and can lead to significant losses. Anti-soiling coatings have been demonstrated to reduce soiling losses and thereby increase PV power production. Objective: This article investigates the applicability of a titanium-dioxide-based anti-soiling coating developed by Photocat under the name “ShineOn” for use with PV installations. The main parameter examined is the optical transmission losses, as this directly translates to performance losses during non-soiled operations. Methods: Measurements of transmittance are carried out using both indoor laboratory setups as well as outdoor PV installations, including measurements of the short-circuit current (Isc), incidence angle modifier (IAM) and spectral transmittance. Investigated samples include both full-sized modules and custom-made mini-modules containing a single solar cell. Results: Both indoor and outdoor measurements show minor transmission losses in the range of 0.3 to 0.6 % and negligible effects on the IAM. Additionally, observations indicate that samples should be coated after lamination, as losses for samples coated before lamination are slightly higher. Conclusion: As the transmission losses due to the ShineOn coating are small and no additional angular- dependent losses were observed, the coating is deemed not to be detrimental for PV applications. Proper assessment of the usefulness requires investigations of the anti-soiling properties, for example, through test installations in regions with high soiling rates.

Continuous-wave Raman amplification in silicon core fibers pumped in the telecom band

Stimulated Raman amplification is observed for the first time in the silicon core fiber (SCF) platform. The SCFs were tapered to obtain sub-micrometer core dimensions and low optical transmission losses, facilitating efficient spontaneous scattering and stimulated Raman amplification using a continuous-wave pump source with milliwatt power levels. A maximum on–off gain of 1.1 dB was recorded at a pump power of only 48 mW with our numerical simulations, indicating that gains up to 6dB are achievable by increasing the fiber length. This work shows that the SCF platform could open a route to producing compact and robust all-fiber integrated Raman amplifiers and lasers across a broad wavelength region.

Detection of OPGW Water Immersion Faults by 1.24/1.625 µm Optical Transmission Loss Measurement

Detection of OPGW Water Immersion Faults by 1.24/1.625 µm Optical Transmission Loss Measurement

The Physics Research of Optical Information Effect at Low Loss in Nonlinear Optical Fiber Transmission

Both nonlinear effects and dispersion are important factors that affect the transmission of optical pulses in optical fibres. In the anomalous dispersion region, the mutual balance of dispersion and nonlinear effects can achieve optical soliton transmission. Starting from the nonlinear Schrodinger equation of the optical pulse, under the condition of ignoring the dispersion, the nonlinear phase shift and frequency chirp of the Gaussian optical pulse under the nonlinear effect of self-phase modulation (SPM) are derived and simulated; the numerical simulation of the SPM the spectrum of Gaussian optical pulses with different maximum phase shifts without chirp and with positive chirp. The study found that the fusion loss of the fibre obtained by this algorithm is less than 0.11dB than that of the traditional single-mode fibre, and the additional bending loss caused by the wavelength range of 1460nm to 1625nm after winding 100 times on a 60mm cylinder is less than 0.02dB/km.

Epitaxy of LiNbO3: Historical Challenges and Recent Success

High-quality epitaxial growth of thin film lithium niobate (LiNbO3) is highly desirable for optical and acoustic device applications. Despite decades of research, current state-of-the-art epitaxial techniques are limited by either the material quality or growth rates needed for practical devices. In this paper, we provide a short summary of the primary challenges of lithium niobate epitaxy followed by a brief historical review of lithium niobate epitaxy for prevalent epitaxial techniques. Available figures of merit for crystalline quality and optical transmission losses are given for each growth method. The highest crystalline quality lithium niobate thin film was recently grown by halide-based molecular beam epitaxy and is comparable to bulk lithium niobate crystals. However, these high-quality crystals are grown at slow rates that limit many practical applications. Given the many challenges that lithium niobate epitaxy imposes and the wide variety of methods that have unsuccessfully attempted to surmount these barriers, new approaches to lithium niobate epitaxy are required to meet the need for simultaneously high crystalline quality and sufficient thickness for devices not currently practical by existing techniques.

The Effects of TeO2 on Polarizability, Optical Transmission, and Photon/Neutron Attenuation Properties of Boro-Zinc-Tellurite Glasses

Boro-zinc-tellurite glasses in the chemical composition of xTeO2–(30 − x)Li2O–20ZnO–50B2O3 (x is ranging from 0 to 20 mol% with step of 5) were systematically studied by means of their optical features such as molar polarizability (αm), molar refraction (Rm), optical transmission (T), metallization principle (M), and reflection loss (RL). Moreover, the Monte Carlo method (via FLUKA code) was applied to investigate the photon and neutron attenuation properties by estimating the mass attenuation coefficient (MAC) of the glasses involved. The MAC values were then utilized to assess various photon attenuation parameters such as HVL, EAN, and MFP. Finally, an extended comparison was achieved between the MFP values of the present glasses and those of various commonly used radiation shields. The results showed that the general trend in MAC throughout the energy spectrum was (TL1)MAC < (TL2)MAC < (TL3)MAC < (TL4)MAC < (TL5)MAC. The TeO2 addition (the substitution of Li2O by TeO2) has a notable impact to increase the LAC values indicating to improve the photon attenuation ability of the current glass specimens. The maximum $${\Sigma_{R} }$$ value was around 0.12 cm−1 for TL1 glass specimen. The investigated glasses could be used for various radiation applications as non-toxic and transparent shields against photon and neutron radiations.

Up-conversion luminescence of neodymium oxide nanocrystals-doped TiO2/ormosils composite films and strip waveguides

Neodymium oxide nanocrystals are synthesized by an inverse microemulsion method. XRD, XPS and HRTEM are used to characterize the properties of the neodymium oxide nanocrystals. Results show that the prepared neodymium oxide particles have obvious "column” structure with a column width of 400 ~ 600 nm and a length of 1 ~ 4 µm and have nanocrystalline structure with a high crystallinity. Neodymium-doped TiO2/organically modified silanes (ormosils) organic–inorganic composite films were prepared by using a sol–gel spin coating method. Up-conversion emission and optical transmittance of the films baked at different temperature were studied. Results indicate that the up-conversion emission occurs at about seven wavelength numbers of 387, 404, 421, 436, 450, 478 and 487 nm, of which the bright blue emission at 436 nm has the strongest intensity. There is a high optical transmittance value of above 88% for all the samples in the wavelength number 500 ~ 1000 nm. Optical waveguide properties including the optical transmission modes and loss of the composite films were measured. The photochemical properties of the composite films were also demonstrated by FTIR spectra. Besides, an energy level diagram was used to explain the mechanism of the up-conversion emission from neodymium oxide nanocrystals. Finally, strip waveguides with different waveguide sizes were built in the composite films through a UV soft nanoimprint technique and the surface morphology of the waveguides was observed by SEM. The as-prepared neodymium-doped composite films have potential applications in the areas of photonics and micro-optical devices.

Colorful solar cells utilizing off-axis light diffraction via transparent nanograting structures

Various colors are implemented in solar cells without optical losses using light diffractions via grating structure. By utilizing the property of diffraction angle variations depending on the diffraction order, wavelength, grating period, and incident angle, many vivid colors are realized at different observation angles. Well-defined grating structures with periods of 770 nm and 1400 nm are uniformly fabricated on Cu(In,Ga)Se 2 thin-film solar cells by a nanotransfer lithography using ZnO nanoparticles. Color-to-angle sensitivity, color brightness, and diffraction efficiency depend on the grating period and incident angle. A wide range of colors, mainly resulting from the 1st-order diffraction are observed in the range of observation angles within 20°. The solar cell performances hardly degrade due to the negligible optical transmission loss in the nanograting structure. The grating applied solar cells show additional advantages: short-circuit current gains in oblique incident light and a self-cleaning effect due to the enhanced hydrophobicity. Through this study, the photovoltaic modules are expected to not only remain as electricity generators, but also become aesthetic structures that can provide aesthetic pleasure to people. • Colors were implemented in solar cells using a transparent nanograting structure. • A ZnO nanograting was simply imprinted on the Cu(In,Ga)Se 2 solar cells. • Many distinct colors were realized at various off-axis observation angles. • Solar cell performances hardly degraded due to negligible optical loss in the grating. • Nanograting enhanced hydrophobicity and optical gain under oblique incident light.

Optical features and nuclear radiation shielding efficiency of ZnO-B2O3-Ta2O5 glasses

This paper reports the optical features and nuclear radiation shielding efficiency of 40ZnO–(60-x)B2O3–xTa2O5, (0 < x ≤ 4) glasses. The optical features of these glasses were examined by evaluating different factors including molar refraction, metallization criterion, molar polarizability, dielectric coefficients (static and optical), optical transmission, and reflection loss. The nuclear radiation shielding efficiency of the tested glasses was estimated by using Geant4 simulations and the XCOM program for varied photons energies. The linear attenuation coefficient and other related factors such as half value layer, effective atomic number, mean free path, electron total stopping powers, and electron continuous slowing down approximation range were calculated over a wide energy range from 15 keV to 15 MeV. The results revealed that the optical dielectric constant of the glasses increased from 1.6536 to 1.6962 as the Ta2O5 increased from 0 to 4 mol%. A notable increase in μ values was observed as the Ta2O5 increased from 0 to 4 mol%. The photon shielding properties of the tested glasses were compared with many samples in terms of MFP. The present glasses showed promising features to apply for optical and radiation shielding applications.

Effect of lead oxide on the optical properties and radiation shielding efficiency of antimony-sodium-tungsten glasses

This paper reports the effect of lead oxide (PbO) on the optical properties and radiation shielding efficiency of Sb2O3–Na2O–WO3–PbO glasses. The optical properties of the glasses were tested by estimating molar refraction (Rm), molar polarizability (αm), metallization principle (M), optical transmission (T), dielectric coefficients (static and optical), and reflection loss (RL). Additionally, the gamma radiation shielding efficiency of the glasses was evaluated via the Monte Carlo method (Geant4 simulations) and the XCOM program. The mass attenuation coefficient (µ/ρ) and other related factors such as effective atomic number (Zeff), half-value layer (HVL), and mean free path (MFP) were calculated at the energy range of 0.25–1.25 meV. Furthermore, the dependence of radiation protection efficiency (RPE) on the thickness of glasses was discussed in detail. The results revealed that at 40 mol% of PbO, the optical transmission was 0.7774 and the reflection loss was 1.1997. A notable increase in RPE as the thickness of the glass changes from 0.5 to 2 cm. The gamma shielding efficiency of the glasses was compared with those of commonly used shields. The reported glasses showed superior properties to apply for radiation shielding applications.

Experimental and Monte Carlo investigations on the optical properties and nuclear shielding capability of Bi2O3[sbnd]Na2O-B2O3[sbnd]Cu2O glasses

In this study, new glasses with a nominal composition of 40Bi2O3–10Na2O-(50-x)B2O3-xCu2O (where 0 > x > 6 wt%), were fabricated by using the standard melt-quench technique. A Bruker XRD diffractometer model AXS D8 Advance was carried out to investigate the amorphous state for the fabricated glasses. The optical features such as bandgap (Eg), molar refraction (Rm), Urbach energy (Eu), metallization principle (M), molar polarizability (αm), optical transmission (T), and reflection loss (RL), were investigated by using the ultraviolet spectrum. The radiation shielding capability of the fabricated glasses was estimated by using FLUKA code and the Phy-X software for varied photon energies. The mass attenuation coefficient (µ/ρ) and other related factors such as half value layer (HVL) and effective atomic number (Zeff) were calculated. The results revealed that there is a notable effect of Cu2O on the optical properties of the glasses involved. As the Cu2O content changed from 0 to 6 mol%, the density of the fabricated glasses increased from 5.128 to 6.214 g/cm3 and the optical transmission decreased from 0.697 to 0.655. On the other hand, the Cu2O content enhanced the nuclear-shielding against gamma-rays. The shielding capability of the fabricated glasses was compared with many samples in terms of MFP. The fabricated glasses showed superior features to apply for optical and gamma shielding applications.

Effect of TiO2/V2O5 substitution on the optical and radiation shielding properties of alkali borate glasses: A Monte Carlo investigation

In this paper, we used Geant4 Monte Carlo simulations to investigate the effect of TiO2/V2O5 substitution on the radiation shielding properties of alkali borate glasses in the chemical form of 30Li2O+55B2O3+5ZnO + xTiO2+(10 − x)V2O5, where x = 0, 2.5, 5, 7.5, and 10 mol%. Also, the optical properties were examined by evaluating several factors such as molar refraction (Rm), metallization criterion (M), molar polarizability (αm), dielectric coefficients (static and optical), optical transmission (T), and reflection loss (RL). The radiation shielding properties of the tested glasses were estimated by determining the mass attenuation coefficient, and other related factors such as the tenth value layer (TVL), the mean free path (MFP), the electron total stopping powers (Ψe) and the electron continuous slowing down approximation range (CSDA) (Φe) for different energy values. The results of Geant4 Monte Carlo were compared with the theoretical values calculated by XCOM platform. The results revealed that the TiO2/V2O5 substitution had a remarkable influence on the gamma shielding properties for the tested glasses. On the other hand, the optical properties slightly changed by the TiO2/V2O5 substitution. The gamma shielding properties of the tested glasses were compared with many samples in terms of MFP. The present glasses showed superior features to apply for optical and radiation shielding applications.

Effect of bismuth oxide on the optical features and gamma shielding efficiency of lithium zinc borate glasses

This paper reports the effect of bismuth oxide (up to 65 mol%) on the optical properties and radiation shielding efficiency of xBi2O3-(65-x)Li2O-20ZnO- 15B2O3 glasses (where x = 45, 50, 55, 60, and 65 mol%). The optical properties of these glasses were examined by evaluating different parameters such as molar refraction (Rm), metallization principle (M), molar polarizability (αm), dielectric coefficients (static and optical), optical transmission (T), and reflection loss (RL). On the other hand, the radiation shielding efficiency of the tested glasses was estimated by using Geant4 simulations and the Phy-X/PSD program for varied photons energies. The linear attenuation coefficient (μ) and other related factors such as half value layer (HVL), effective atomic number (Zeff), and mean free path (MFP) were calculated over a wide energy range from 15 keV to 15 MeV. The results revealed that the optical dielectric constant of the glasses increased from 3.1469 to 3.2076 as the Bi2O3 increased from 45 to 65 mol%. A notable increase in μ values was observed as the Bi2O3 increased from 45 to 65 mol%. The photon shielding properties of the tested glasses were compared with many samples in terms of MFP. The present glasses showed superior features to apply for optical and radiation shielding applications.

Role of ZnO on TeO2.Li2O.ZnO glasses for optical and nuclear radiation shielding applications utilizing MCNP5 simulations and WINXCOM program

The role of ZnO on the [(100-(X + 15)] TeO2-15Li2O-XZnO: X = 00, 05, 10, 15, 20, and 25 mol% (TLZ) glasses for optical and gamma-rays shielding applications was investigated. Molar refraction and molar polarizability (RMolar, αMolar); Dielectric coefficients and metallization principle (εStatic, MCriterion); Optical transmission and reflection loss (TOptical, RLoss); Metallization property according to refractive index and optical energy gap (M(nLinear), M(EOptical)) were investigated. The nuclear radiation shielding features were investigated for the proposed glasses utilizing MCNP5 simulations and WinXCOM program. The mass attenuation coefficient and effective atomic number ((μ/ρ, Zeff); Half-value layer and mean free path (HVL, MFP); Energy-absorption buildup factor and exposure buildup factor (EABF, EBF) were evaluated for all TLZ glasses. Results revealed that the RMolar changed from 15.981 to 18.70 cm3/mol, while αMolar changed from 6.342 to 7.250×10−24 cm3 for TLZ60 to TLZ85. The TOptical varied from 0.751 to 0.739, while RLoss varied from 0.141 to 0.150. All studied samples are in non-metallic (insulator) nature where RMolar values are smaller than that of VMolar (24.234–27.138 cm3/mol). TLZ glasses with the highest concentrations of ZnO have the highest (µ/ρ) values and lowest HVL and MFP. Thus, TLZ glasses exhibit higher shielding capacity among other commercial materials as RS-360.

Radiation attenuation and optical features of lithium borate glasses containing barium: B2O3.Li2O.BaO

The influence of BaO on the optical characteristics and nuclear radiation shielding properties for 60B2O3-(40-x)Li2O-xBaO: x = 0, 5, 10, 15, and 20 mol% glasses was investigated. Various optical parameters such as optical transmission and reflection loss (TOptical, RLoss), molar refraction and molar polarizability (RMolar, αMolar), optical and static dielectric coefficients and metallization criterion (εOptical, εStatic, MCriterion), and metallization property according to refractive index and optical energy gap (M(nLinear), M(EOptical)), were determined. The results confirmed that RMolar changes directly with αMolar, while TOptical changes inversely with RLoss. The mass attenuation coefficient (μ/ρ) was investigated using WinXCOM software and the results showed that all the S1–S5 glasses have good attenuation ability at 284 keV due to their high mass attenuation coefficients (μ/ρ). The highest and lowest values of μ/ρ occurred at 284 keV and 1.33 MeV respectively and varied between 0.1055 and 0.1361 cm2/g and 0.0526–0.0534 cm2/g. The linear attenuation coefficient (μ) increased with the gradual addition of BaO from glass S1→S5. The results showed that the effective atomic number (Zeff) for S1 is almost constant, while S5 possessed the highest Zeff values. The half value layer (HVL) was estimated and the effect of BaO on this parameter was analyzed. At 284 keV, the HVL values were 2.8192, 2.3847, 2.1597, 1.9687 and 1.8936 cm for S1–S5 glasses respectively. The S5 sample possessed the least HVL, and accordingly, had better attenuation capabilities than the S1–S4 samples. Therefore, lithium borate glasses with high concentration of BaO can be applied in several optical and medical applications.

Onset of Fogging and Degradation in Polyvinyl Toluene-Based Scintillators

Plastic-based gamma-ray detector materials such as polyvinyl toluene (PVT) occasionally suffer from loss of optical light transmission due to internal defects or “fogging” when exposed to some environmental conditions over time. Fogging results in reduced scintillation light propagated to the photomultiplier tube for collection. Investigations of the physical cause of these defects and their associated environmental conditions are ongoing. The goal of this article was to characterize the signs and effects of fogging over a simulated 22-year lifespan of the PVT in outdoor environments. Two potential mitigation methods were also evaluated, and one successfully mitigated the phenomena.

PMMA Thin Film with Embedded Carbon Quantum Dots for Post-Fabrication Improvement of Light Harvesting in Perovskite Solar Cells.

Perovskite solar cells (PSCs) with a standard sandwich structure suffer from optical transmission losses due to the substrate and its active layers. Developing strategies for compensating for the losses in light harvesting is of significant importance to achieving a further enhancement in device efficiencies. In this work, the down-conversion effect of carbon quantum dots (CQDs) was employed to convert the UV fraction of the incident light into visible light. For this, thin films of poly(methyl methacrylate) with embedded carbon quantum dots (CQD@PMMA) were deposited on the illumination side of PSCs. Analysis of the device performances before and after application of CQD@PMMA photoactive functional film on PSCs revealed that the devices with the coating showed an improved photocurrent and fill factor, resulting in higher device efficiency.