Glass Optical Fibers Research Articles

Optical camera communication (OCC) using a laser-diode coupled optical-diffusing fiber (ODF) and rolling shutter image sensor.

We demonstrate an optical-camera-communication (OCC) system utilizing a laser-diode (LD) coupled optical-diffusing-fiber (ODF) transmitter (Tx) and rolling-shutter based image sensor receiver (Rx). The ODF is a glass optical fiber produced for decorative lighting or embedded into small areas where bulky optical sources cannot fit. Besides, decoding the high data rate rolling-shutter pattern from the thin ODF Tx is very challenging. Here, we propose and experimentally demonstrate the pixel-row-per-bit based neural-network (PPB-NN) to decode the rolling-shutter-pattern emitted by the thin ODF Tx. The proposed PPB-NN algorithm is discussed. The proposed PPB-NN method can satisfy the pre-forward error correction (FEC) BER at data rate of 3,300 bit/s at a transmission distance of 35 cm. Theoretical analysis of the maximum ODF Tx angle is also discussed; and our experimental values agree with our theoretical results.

Tunable Multi-Band-Stop Filters Using Generalized Fibonacci Photonic Crystals for Optical Communication Applications

In this study, a numerical investigation of photonic quasi-periodic Generalized Fibonacci (GF) (m, n) sequences is carried out in the visible spectrum. The transfer matrix method is employed to study the behavior of wave propagation through the photonic structures. Firstly and to highlight the importance of the GF structure, its transmittance spectrum is compared to those of periodic and ordinary Fibonacci structures. It is shown that the GF structure permits one to obtain multi-photonic band gaps (PBGs) separated by several resonance modes. The variation in the parameter m of the GF (m, 1) structure allows for the tuning of the number, the position and the width of these bands. By changing the parameter m, the wavelengths (650, 850, 1300, and 1550 nm) of the plastic and glass optical fibers can be allowed or forbidden to transmit through the structure according to the value of this parameter. In contrast, the variation in the parameter n for GF (1, n) hides all PBGs and only permits the appearance of several Kiessig fringes. The proposed structures can find application as tunable multi-band-stop filters for optical fiber wavelengths.

Fabry-Perot Interference Fiber Acoustic Wave Sensor Based on Laser Welding All-Silica Glass

Due to the small difference between the thermal expansion coefficients of silica optical fiber and silica glass, they are used as probe materials of optical fiber acoustic wave sensors. According to the light absorption characteristics of a pressure-sensitive silica diaphragm and silica glass, the laser welding of an all-silica Fabry–Perot (FP) interference optical fiber acoustic wave sensor with a CO2 laser is proposed. For understanding the influence of thermal expansion of sealing air in an FP cavity and the drift of interference-intensity demodulation working point of a FP interference acoustic wave sensor, we designed a process for the laser welding of an ultra-thin silica diaphragm and sleeve and optical fiber and sleeve. The exhaust hole of the FP cavity is reserved in the preparation process, and an amplified spontaneous emission light source and a tunable optical-fiber FP filter are introduced to stabilize the working point. The sensor is tested with a 40 kHz sound vibration signal. The results show that the sound pressure sensitivity of the sensor to an acoustic source of 0.02–0.1 W/cm2 is 6.59 mV/kPa. The linearity coefficient is 0.99975, indicating good linearity.

Simultaneous modal phase and group velocity matching in microstructured optical fibers for second harmonic generation with ultrashort pulses.

Optical fibers provide a favorable medium for nonlinear optical processes owing to the small mode field size and concurrently high optical intensity combined with the extended interaction lengths. Second harmonic generation (SHG) is one of those processes that has been demonstrated in silica glass optical fibers. Since silica is centrosymmetric, generating SHG in an optical fiber requires poling of the glass. In addition and when one wants to use ultrashort pulses for SHG, achieving both phase and group velocity matching is crucial. Although fibers that feature either modal phase velocity or group velocity matching for SHG have been reported, the possibility of simultaneous modal phase and group velocity matching was never reported before. In this paper we address this challenge, and for the first time to our knowledge, we show that it is feasible to do so with silica microstructured optical fibers featuring at least one ring of air holes in the cladding and a heavily Germanium doped core (above 25 mol.%) by exploiting the LP01(ω) and LP02(2ω) modes at 1.06 µm pump and 0.53 µm second harmonic wavelengths. This finding can greatly impact applications requiring waveguide based SHG generation with ultrashort pulses, including microscopy, material characterization and nonlinear imaging.

Image Spherizing-Based Three-Dimensional Displacement Measurement Technique for Microscope with Single Camera

The detection of three-dimensional displacement, caused by micro-nano scale deformation, is of great significance for the industrial production of glass or quartz optical fiber products. Considering the detection cost and practicability, an image spherizing-based three-dimensional displacement measurement method for a monocular microscopic imaging system (a microscope with a normal industrial camera) is proposed. Differential theory tells us that an arbitrary large-scale deformation can be approximatively considered as the sum of slope-shaped deformations. In this paper, an ordinary slope model is presented by the idea of image spherizing and differential theory, which reveals the mathematical relation between in-plane displacement and out-of-plane displacement in the deformed images captured by an optical microscope. After obtaining the in-plane displacement field, the out-of-plane displacement field can be extracted from the in-plane displacement field by the ordinary slope model, which indicates that the out-of-plane displacement information carried by the in-plane displacement is fully utilized. Simulation and application experiments are performed to demonstrate the effectiveness and all the absolute errors of the measurement by optical microscope with a magnification of 50× are less than 0.2 μm. Unlike conventional methods, the new method does not need a phase unwrapping process during detection and has many attractive characteristics such as low-cost, simple arrangements and good applicability. Because the measurement precision of this technique can meet the detection requirement, it has been applied to the industrial detection of glass or quartz optical fiber products.

Suppression of Rayleigh Scattering in Silica Glass by Codoping Boron and Fluorine: Molecular Dynamics Simulations with Force-Matching and Neural Network Potentials

Rayleigh scattering attributed to the density fluctuation of silica glass is considered as the intrinsic origin of optical loss in glass fiber. Therefore, minimizing the density fluctuation is key to improving the information and telecommunications networks. In this study, classical molecular dynamics (MD) simulations were employed to theoretically examine the effectiveness of codoping boron and fluorine for ameliorating the homogeneity of silica glass. For the MD simulations, the force-matching potential (FMP) with a Buckingham formula was developed by optimizing the parameters to reproduce the force and energy calculated by the density functional theory (DFT). The accuracy of the FMP was confirmed via comparisons with available experimental data as well as glass models constructed using the neural network potential, which was superior in reproducing the force and energy of the DFT data to the FMP. As a result, the small amount of boron and fluorine added to the silica glass was found not to deteriorate the density fluctuation of silica glass. The additives reduce the viscosity of silica glass, which leads to a lower fictive temperature and, thus, to a better homogeneity. Consequently, the codoping of boron and fluorine was suggested as a possible solution to suppress the Rayleigh scattering of optical glass fiber.

Omnidirectional High Reflectors Using Silica/Superconductor Fibonacci Photonic Crystal for Optical Communication Applications

Using the transfer matrix method and Fibonacci structure, an omnidirectional high reflector that covers the fiber optics wavelengths is searched. We aim to make the reflector covers the operating wavelengths of Plastic and Glass fiber optics (650, 850, 1300 and 1550nm). Firstly, an ordinary Fibonacci structure composed of TiO2 and SiO2 slabs materials was studied and for TE and TM polarization modes the reflectance spectra cover only the 850, 1300 and 1550 nm wavelengths and for a limited range of wave-angle of incidence. Secondly, the SiO2 slabs were replaced with the superconductor YBCO slabs which allows the extension of the reflectance bands to cover all fiber optics wavelengths for the entire angle of incidence interval [0-1.5 radian] and for both polarization modes. During that, the structure thickness was optimized by varying the iteration number and the optical thickness of Fibonacci sequence. Finally, the optical behavior of the reflector was tested when changing the ambient temperature.

Silica incorporation into sodium aluminum phosphate glasses: Structural characterization by Raman spectroscopy and multinuclear solid-state NMR

Optical fiber glasses in the system (59-xP2O5)-xSiO2–13Al2O3-28Na2O show non-linear trends in the glass-transition temperatures, thermal expansion coefficients, and weathering stabilities. The structural origins have been studied using solid-state NMR and Raman spectroscopies on a series of bulk glasses with 0 ≤ x ≤ 13. Two types of P2 units – those dominantly interacting with Na+and those interacting more strongly with Al can be differentiated by 31P{23Na} and 31P{27Al} double resonance experiments. Silicon is four-coordinated, fully polymerized, and engaged in Si-O-P linkages. Trends in the 29Si chemical shifts and the 31P-31P dipolar interaction strengths are related to the Si-O-P, Si-O-Al, and P-O-P connectivity distributions, providing a rationale for changes in macroscopic properties.

Tunable nanopillar array on a quartz-fiber tip for surface enhanced Raman scattering (SERS) detection

Abstract In this work, a simple two-step method to create tunable self-assembled three-dimensional nanostructure array-like nanoantennas directly on the tip of an optical quartz glass fiber is described. The structures are prepared by using dry etching of the fiber tip. For the etching process, gold nanoparticles fabricated by thermal dewetting technique were used as template. The structures are applied as sensors for label-free analysis of organic substances in ppb range, such as drug residues in liquid solutions. The measurements are carried out by a portable Raman device with an exchangeable sensor head utilizing the SERS-effect. This method allows in situ applications. In order to characterize the SERS cells, para-thiocresol and diclofenac sodium are used as model substances. For optimization of the substrate performance, different thicknesses of the dewetting-layer (6, 9, 12 nm), different etching times for formation of the pillars (6, 8, 10 and 12 min), and different thicknesses of SERS-metallization (25, 50, 75 nm) of gold and silver are compared. In order to show the applicability of the structure on the tip of a fiber, measurements from the upper side and from the underside of the substrate on quartz plates are compared. Reproducible SERS enhancement factors up to 10 7 {10^{7}} were achieved.

Multifunctional optrode for opsin delivery, optical stimulation, and electrophysiological recordings in freely moving rats

Objective. Optogenetics involves delivery of light-sensitive opsins to the target brain region, as well as introduction of optical and electrical devices to manipulate and record neural activity, respectively, from the targeted neural population. Combining these functionalities in a single implantable device is of great importance for a precise investigation of neural networks while minimizing tissue damage. Approach. We report on the development, characterization, and in vivo validation of a multifunctional optrode that combines a silicon-based neural probe with an integrated microfluidic channel, and an optical glass fiber in a compact assembly. The silicon probe comprises an 11-µm-wide fluidic channel and 32 recording electrodes (diameter 30 µm) on a tapered probe shank with a length, thickness, and maximum width of 7.5 mm, 50 µm, and 150 µm, respectively. The size and position of fluidic channels, electrodes, and optical fiber can be precisely tuned according to the in vivo application. Main results. With a total system weight of 0.97 g, our multifunctional optrode is suitable for chronic in vivo experiments requiring simultaneous drug delivery, optical stimulation, and neural recording. We demonstrate the utility of our device in optogenetics by injecting a viral vector carrying a ChR2-construct in the prefrontal cortex and subsequent photostimulation of the transduced neurons while recording neural activity from both the target and adjacent regions in a freely moving rat for up to 9 weeks post-implantation. Additionally, we demonstrate a pharmacological application of our device by injecting GABA antagonist bicuculline in an anesthetized rat brain and simultaneously recording the electrophysiological response. Significance. Our triple-modality device enables a single-step optogenetic surgery. In comparison to conventional multi-step surgeries, our approach achieves higher spatial specificity while minimizing tissue damage.

Development of real-time measurement system for emission and absorption of visible light during heavy gamma-ray irradiation

A system for the real-time measurement of the visible light emission from and absorption by a material in an intense gamma-ray field was developed. A white light-emitting diode produces a visible light beam that passes through an irradiated specimen and is measured by an ultraviolet–visible spectrophotometer through a long glass optical fiber accompanied with a Pb shielding configuration. A video camera provides real-time visual observation of the gradual change in the color state of the irradiated specimens. In order to study the formation of silver nanoparticles in detail, blue color dye was added to the radiolytic medium and its color change was examined as a function of irradiation dose to observe the interaction among radiation-introduced radicals in water, generated silver nanoparticles, and dye molecules. A mutual impact between the formation of silver nanoparticles and the deformation of the dye during gamma radiolysis are experimentally clarified. The combination of direct visual observation and optical absorption measurement is expected to provide powerful clues for elucidating various phenomena caused by irradiation effects.

Performance of Pellucid Concrete by using Optical Fibers

Energy efficient building and aesthetic view are the vital knot for infrastructure. Now engineers have developed smart translucent concrete(STC) using glass optical fibers (GOF). It can able to transmit light from one phase to the other phase of the wall. Smart translucent concrete is also known as pellucid concrete. Pellucid concrete reduces the consumption of electricity. Source of light can be taken from natural sunlight and artificial light source from LED having 20w. In this investigation, incorporating optical fibers in various diameters are 1.5 mm and 2.5 mm. Concrete cube with provision of hole for providing glass optical fiber and arranged in equal spacing of about 15 mm and 25 mm. In this experiment, analysis the performance of smart translucent concrete in the aspect of strength and luminance. The light intensity from the specimen can be measured with a help of photometer. It is an energy efficient building material innovated in recent years.

DETECTION OF DISPLACEMENT USING GLASS OPTICAL FIBER SENSOR WITH VARIOUS CONFIGURATION

The research has measured the landslide using a displacement sensor based on Glass Optical Fiber (GOF) and Optical Time Domain Reflectometer (OTDR). The sensor manufacture process consists of various materials, structures, configurations, diameters, and directions. The sensor is made using GOF with a single-mode structure and single mode-multimode-Singlemode (SMS) structure. Each system is given a variety of configurations, namely gamma, bowknot, and three loops configuration. Each arrangement is provided a variation of the indentation diameter in three displacement directions. The test results will be read as the power loss on the OTDR in dB units. The results obtained were then compared between two materials, two structures, and directions. Displacement resulting landslides and changes to the sensor, causing power losses, and affecting the characteristics of each sensor. We found the best measurement results with the sensitivity value of 0.241 dB/mm and the resolution value of 0.004 mm. The displacement sensor has been made for measuring landslide in the laboratory-scale simulation based on GOF and OTDR with easier fabrication, easy operation, high sensitivity, better resolution and can be connected to a computer

Structure and properties of new fluoro-sulfo-phosphate laser glasses

<p indent=0mm>Rare-earth-doped fluoro-sulfo-phosphate (FSP) glass is characterized by excellent spectroscopic properties and high thermal and chemical stabilities. Therefore, it is a potential candidate for laser glass and high-gain active optical fiber matrix. However, the underlying contributions of compositional variations to the structure and properties of FSP glass systems are still indistinct owing to their complex mixed-anion nature. Herein, the glass-forming region, structure, physical, and luminescent properties of several FSP glasses are characterized. The results show that FSP glasses possess the advantages of fluoro-phosphate glasses such as high rare-earth ion solubility, low refractive index and phonon density of states. Meanwhile, the mixed-anion structure improves the thermal and chemical stabilities, elastic modulus and spectroscopic parameters. The fabricated FSP samples have good glass-forming ability, low nonlinear refractive index (minimum: <sc>1.2×10⁻¹³ esu</sc>), good thermal stability (∆<italic>T</italic>_max=181°C), chemical stability (DR_min=<sc>0.7×10⁻⁷ g cm⁻² min⁻¹</sc>) and relatively high elastic modulus (<italic>E</italic>_max<sc>=68.8 GPa).</sc> The maximum emission cross-section of Nd³⁺:⁴F_3/2 →⁴I_11/2 is <sc>3.3×10⁻²⁰ cm²,</sc> effective linewidth is <sc>32.1 nm,</sc> lifetime is <sc>372 μs</sc>, and FOM and gain bandwidth are <sc>1.2×10⁻²³ s cm²</sc> and<sc>105.9×10⁻²⁷ cm³,</sc> respectively. These results are higher than those of phosphate or fluoro-phosphate laser glasses, indicating the broad application prospects of FSP glasses in laser glass, fiber lasers and amplifiers.

Fabrication of an SPME fiber based on ZnO@GA nanorods coated onto fused silica as a highly efficient absorbent for the analysis of cancer VOCs in water and urine

Analysis of volatile organic compounds (VOCs) secreted in urine, blood, breath, etc. is a new method for monitoring the metabolism and biochemistry of the human body. However, due to the complexity of samples, a pre-concentration step is necessary before the final analysis with gas chromatography-mass spectroscopy (GC-MS). Therefore, miniaturized extraction methods such as solid-phase microextraction (SPME) can be a promising and simple pre-concentration technique. Different strategies have been adopted for the fabrication or modification of SPME fibers. This study presents the preparation and characterization of glass optical fibers coated with ZnO nanorods functionalized with gallic acid (ZnO@GA nanorod) as SPME adsorbent in GC-MS. ZnO@GA nanorods were synthesized separately and then coated onto the fibers. The coated fibers were characterized by using field emission scanning electron microscopy coupled with energy dispersive analysis of X-rays (FESEM/EDAX) and Fourier transform infrared spectroscopy (FTIR) techniques. Possessing a high surface to volume ratio of ZnO nanorods and functional groups of GA, the ZnO@GA nanorod-based SPME fibers exhibited good extraction performance for VOCs comparing with the commercial polydimethylsiloxane (PDMS) coated fibers. Under optimal conditions (NaCl concentration, 30% w/v; extraction time of 25 min; pH, 5–7 and stirring rate of 400 rpm) ZnO@GA nanorods coated fibers achieved low detection limits (0.32–4.8 μg/L), low quantification limits (1.8-16.3 μg/L) and good linearity (5–1000 μg/L) for selected VOCs. The repeatability (n = 3) for a single fiber was within the range of 4.1–7.9% (intra-day) and 5.7–9.6% (inter-day) while the reproducibility (n = 3) of fiber-to-fiber were in the range of 4.7% and 9.9%. This method was successfully used for the determination of six VOCs in water and urine with satisfactory recoveries of 90–112%. ZnO@GA nanorod coated fibers, despite possessing a much thinner coating compared to the commercial fibers, revealed a better overall extraction efficiency towards VOCs. These results indicated that the ZnO@GA provided a promising alternative in sample pretreatment and analysis in GC-MS.

Analysis and experiment on simultaneous measurement of strain and temperature by etched and un-etched FBG pair

This paper presents analysis and experiment on simultaneous measurement of strain and temperature using pair of etched and un-etched fiber Bragg grating (FBG) fabricated in a single mode glass optical fiber. The intrinsic sensitivity for strain and temperature of FBG explicitly depends on the clad diameter. The mechanical properties of glass optical fiber such as Young’s modulus and Poisson’s ratio change with cladding diameter. This in turn will change the strain optic coefficient and thermal expansion coefficient of the optical fiber. Analytically, it is shown that the change in refractive index, Young’s modulus, Poisson’s ratio and thermal expansion coefficient was 0.04, 58.2 GPa, 0.29 and 0.99 × 10−6/°C respectively as the cladding diameter was decreased from 125 µm to 11 µm. The results obtained for strain and temperature sensitivity from the analysis are verified with experimental results. Experimentally, as the fiber clad diameter is reduced from 125 µm to 25 µm via hydrofluoric (HF) etching, the average strain sensitivity increases from 1.06 pm/µɛ to 1.20 pm/µɛ for the maximum applied strain of around 5500 µɛ and also the average temperature sensitivity increases from 11.48 pm/°C to 11.80 pm/°C for the maximum applied temperature of 150 °C. The temperature and strain can be measured simultaneously with high accuracy by using these sensitivity coefficients for two gratings.

Distributed polymer optical fiber sensors: a review and outlook

Aging degradation and seismic damage of civil infrastructures have become a serious issue for society, and one promising technology for monitoring their conditions is optical fiber sensing. Glass optical fibers have been predominantly used for the past several decades to develop fiber sensors, but currently polymer or plastic optical fibers (POFs) have also been used extensively to develop advanced fiber sensors because of their unique features, such as high flexibility, large breakage strain, and impact resistance. This review focuses on recently developed distributed and quasi-distributed POF-based sensing techniques based on Rayleigh scattering, Brillouin scattering, and fiber Bragg gratings.

Optical Measurements

Optical sensing techniques are used in a large variety of application fields where fast, portable, remote-sensing, low-cost and/or rugged devices are required for detection, identification, and measurements of a variety of parameters. Sensors based on optical fibers are exploited in demanding applications, including pharmaceutical research, medical diagnostics, environmental monitoring, structural health monitoring, physical parameters detection, industrial applications, food safety and security. In these instances, sensors systems often benefit from the versatility of glass, plastic or specialty optical fibers.

Beyond near-infrared lossy mode resonances with fluoride glass optical fiber.

The objective of this Letter consists of the exploration of the lossy mode resonance (LMR) phenomenon beyond the near-infrared region and specifically in the short wave infrared region (SWIR) and medium wave infrared region (MWIR). The experimental and theoretical results show for the first time, to the best of our knowledge, not only LMRs in these regions, but also the utilization of fluoride glass optical fiber associated with this phenomenon. The fabricated devices consist of a nanometric thin-film of titanium dioxide used as LMR generating material, which probed extraordinary sensitivities to external refractive index (RI) variations. RI sensitivity was studied in the SWIR and MWIR under different conditions, such as the LMR wavelength range or the order of resonance, showing a tremendous potential for the detection of minute concentrations of gaseous or biological compounds in different media.

On complex wave solutions depicted by the variable coefficients coupled Hirota equation

In this paper, the variable coefficients coupled Hirota equation is investigated by virtue of the unified method. Playing an important role in optics, the coupled Hirota equation describes the transmission process when high intensity ultra-short pulses pass through an optical glass fiber. Two types of complex wave solutions, polynomial function and rational function solutions, are gained. The polynomial function solutions incorporate complex solitary, complex soliton and complex elliptic wave solutions, while the rational function solutions involve complex periodic and complex soliton wave solutions. Furthermore, by choosing different values of the parameters, we illustrate the dynamical behaviors and the physical signification of these solutions.