Silica-based optical fibers with an ultra-high Yb concentration were systematically studied. Three the most commonly used in industry glass matrixes for active fiber core were investigated: ...aluminosilicate, phosphosilicate and aluminophosphosilicate. For all the glass hosts optical fibers doped with a record high concentration of Yb in a glass core were fabricated utilizing an all-gas-phase deposition based on MCVD technology. The factors limiting increase of Yb content in glasses and fibers were revealed. For the first time it was shown that highly Yb-doped fibers could nearly completely lose their active properties and the most probable reason for that is concentration quenching of luminescence.
The research and development of nanofibers has gained much prominence in recent years due to the heightened awareness of its potential applications in the medical, engineering and defense fields. ...Among the most successful methods for producing nanofibers is the electrospinning process. In this timely book, the areas of electrospinning and nanofibers are covered for the first time in a single volume. The book can be broadly divided into two parts: the first comprises descriptions of the electrospinning process and modeling to obtain nanofibers while the second describes the characteristics and applications of nanofibers. The material is aimed at both newcomers and experienced researchers in the area.
Owing to environmental concerns caused by the use of synthetic fibers, there is an urgent need to find new eco-friendly fibers. In addition, conventional cellulosic fibers are becoming costly due to ...an increase in production cost, therefore, sustainable alternative sources of eco-friendly fibers need to be explored. This study investigates the extraction and characterization of fibers from the Cyperus papyrus plant and evaluates its potential as textile fibers. Cyperus papyrus plant fibers were extracted using water retting and alkaline extraction methods and their mechanical, physical, thermal, and chemical properties were studied. The fiber's chemical composition was established and alkaline extracted fibers contained 61.82% cellulose, 11.82% hemicellulose, 23.6% lignin, 3.86% ash, and 2.75% extractive while the water-retted fibers contained 57.98% cellulose, 13.45% hemicellulose, 25.42% lignin, 6.07% ash, and 3.15% extractive. The fineness of the extracted fibers was 8.38 and 7.31 Tex for water-retted and for alkaline extracted fibers, respectively. The average tensile strength of the extracted fibers ranged from 26.25 to 31.05cN/Tex. The average elongation of the fibers was between 2.02% and 2.79% while its thermal degradation temperature was as high as 150ºC. Compared with conventional fibers, the extracted fibers have the potential of replacing them based on the properties studied.
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Environmental awareness across the world has motivated researchers to focus their attention on the use of cellulosic fiber as reinforcement in polymer matrices. Lignocellulosic fibers are an ...abundantly available resource in all countries, which is cheap and easily renewable. Also, due to their properties, cellulosic plant fibers exhibit a great potential for use in polymer reinforcement. As a result, considerable research and development efforts have been directed towards the use of cellulosic fibers as a reinforcing material in composites. The use of cellulosic fiber reinforced composites has continuously increased during recent years, which benefits the cultivation of fiber plants and the economy of the country. This research area continues to be of interest to both industry and academia, the use of cellulosic fibers in composite applications being investigated throughout the world. Cellulosic fiber reinforced composites are reasonably strong, lightweight, harmless to human health and the environment, and biodegradable, hence they have the potential to be used in various applications. Recent progress in cellulosic fiber composites research has illustrated their great potential as structural components in automobiles, aerospace structures, construction, and building, and so forth. This study is an effort to create awareness about the research works that have been published in the field of natural fiber composites. This review briefly illustrates the main paths and results of major research published in the field of natural fiber reinforced polymer composites. The topics covered include the aspects of fiber treatment to improve the mechanical properties of the composites, manufacturing methods, performance of hybrid composites, effect of laminate configuration, and many different applications of natural fiber composites. By presenting a systematic view of the work performed in this area so far, this review will hopefully serve as a starting point for the development of new ideas in the research on natural fiber polymer composites.
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In optical fiber, the Orbital Angular Momentum (OAM) mode is a special mode with spatially infinite orthogonality. It provides a new multiplexing method to the communication capacity shortage problem ...and solves the complexity and high energy loss of OAM beams in space. In the past few years, lots of researchers studied OAM generation technology, including phase element coupling method, fiber grating method, optical coupling conversion method, and photonic crystal fiber method. This article provides a comprehensive review of the basic principles of OAM fiber design, the generation technology of OAM beams in optical fibers, and finally discusses the challenges and application prospects. The purpose of this paper is to provide reference and guidance for related experiments of OAM beams in the future.
The unique characteristics of hollow core fibers lead to low non-linearity and reduced sensitivity to environmental influences, making them attractive platform for designing inline fiber optic ...devices. Among these, an inline fiber polarizer would be most desired for applications such as gyroscopes, interferometric sensors and telecommunication. Hollow-core fiber polarizers, demonstrated to date, suffer from high insertion loss (>5 dB) for the pass polarization, and typically require tens of meters long nested antiresonant fiber to achieve a meaningful polarization extinction ratio (PER) >20 dB. We report a novel approach that makes use of intricate modal loss spectrum within a resonant band of single-ring antiresonant fiber to realize the first high-performance, discrete hollow-core fiber polarizer. The compact device comprising only 6 cm long fiber offers a high PER of >25 dB with <1 dB transmission loss for the pass polarization. In the present form, the polarizing action takes place over 14 nm and 7 nm bandwidth in the 2 μm and 1 μm wavelength range, but the simplicity of design principles makes it straightforward to shift the operating wavelengths to practically any wavelength band. The device can be fusion spliced with a standard antiresonant hollow-core fiber and a large mode area solid-core fiber with splice loss of 0.14 dB and 0.45 dB respectively. Complete integration of the proposed device into an all hollow-fiber setup would lead to a total insertion loss of 1.3 dB including both input and output splicing, which is the lowest for a discrete hollow-core fiber polarizer reported so far. The results encourage the development of other hollow-core fiber components by exploiting the unique characteristics cultivated in a resonant band of an antiresonant fiber.
A distributed sensor system for detecting and locating intruders based on the phase-sensitive optical-time-domain reflectometer (/spl phi/-OTDR) is described. The sensing element is a cabled ...single-mode telecommunications fiber buried along the monitored perimeter. Light pulses from a continuous-wave Er:fiber Fabry-Pe/spl acute/rot laser with a narrow (/spl ap/3 kHz) instantaneous linewidth and low (few kilohertz per second) frequency drift are injected into one end of the fiber, and the backscattered light is monitored with a photodetector. The effect of phase changes resulting from the pressure of the intruder on the ground immediately above the buried fiber are sensed by subtracting a /spl phi/-OTDR trace from an earlier stored trace. In laboratory tests with fiber on reels, the effects of localized phase perturbations induced by a piezoelectric fiber stretcher on /spl phi/-OTDR traces were observed. In field tests, people walking on the ground above a buried fiber cable induced phase shifts of several-/spl pi/ radians.
Electrostriction in an optical fiber is introduced by interaction between the forward propagated optical signal and the acoustic standing waves in the radial direction resonating between the center ...of the core and the cladding circumference of the fiber. The response of electrostriction is dependent on fiber parameters, especially the mode field radius. We demonstrated a novel technique that can be used to characterize fiber properties by means of measuring their electrostriction response under intensity modulation. As the spectral envelope of electrostriction-induced propagation loss is anti-symmetrical, the signal to noise ratio can be significantly increased by subtracting the measured spectrum from its complex conjugate. We show that if the transversal field distribution of the fiber propagation mode is Gaussian, the envelope of the electrostriction-induced loss spectrum closely follows a Maxwellian distribution whose shape can be specified by a single parameter determined by the mode field radius.
High-power single-frequency fiber lasers with exceptional properties, such as mode-hop-free and narrower linewidths, lower noise, and compact all-fiber designs, have been attractive in many ...applications, including high-resolution sensing, coherent telecommunications, optical frequency domain reflectometry, and as a seed laser for light detection and ranging (LIDAR). However, the development of high-power single-frequency fiber lasers is constrained greatly by the lack of high-gain optical fiber and components. In this review, we discuss the basic considerations of advanced techniques for soft glass fiber and fiber preform as well as three key issues among them. Then, the recent advances in RE-doped soft glass and fiber lasers operating at near-infrared (NIR) and mid-infrared (MIR) wavelengths are evaluated in detail. Finally, prospects, applications and challenges for the realization of high-efficiency soft optical fibers in single-frequency fiber laser applications are analyzed and discussed. The review is organized as follows: Sections 1–3 introduce the basic requirements for the rare-earth (RE) ions and host matrix material for obtaining efficient NIR-MIR laser output, a review of the background of processing fundamentals on the fabrication and characterization for newly developed soft optical glass fibers, an outline of the key issues of platinum removal and the dehydration technique, effective doping of RE, and low splicing loss together with the recent theoretical and experimental results. Section 4 summaries the design and development of RE-doped soft optical glass and fiber lasers operating at 1, 1.5, 2, and 3 μm with emphatical discussions on the related luminescence mechanism and laser foundation as well as single-frequency lasers. Section 5 reviews the recent progress of various novel glass fibers and fiber lasers with unique photoelectricity properties, such as transparent glass-ceramic fiber and fiber lasers, quantum-dot fiber and fiber lasers, Bi-doped fiber and fiber lasers, as well as other novel glass fibers and devices, and outlines their prospects, applications, and challenges. Furthermore, Section 6 presents the conclusions of this review, which include the following: (1) From the single-component silica fiber to the multicomponent soft optical glass fiber, the glass compositions become more and more complex and the corresponding preparation method is constantly developing and improving. Various new types of optical fiber materials and components greatly expand their applications in the fields of fiber amplifiers, fiber lasers, and nonlinear optics, etc. (2) High-gain optical fiber is the key to the development of high-power single-frequency fiber lasers. To achieve intense and highly-efficient luminescence and lasers at the NIR and MIR regions from soft glass and optical fiber, the following methods were adopted, including using RE sensitization, uniform doping with high-concentration RE, hydroxyl and impurity-removing, new optical fiber and laser cavity design, low fusing loss, and the high-efficiency pumping method, etc. These novel glass systems and luminescence mechanisms enrich the glass systems of the past and provide a wealth of valuable data for optoelectronic materials and devices.
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A high-efficiency grating fabrication method was, for the first time, demonstrated to inscribe helical long period fiber gratings (H-LPFGs) in small numbers by means of twisting a standard ...single-mode fiber (SMF) during hydrogen-oxygen flame heating and then cutting the helical fiber into in series of sections. Each section of the helical fiber was a desired LPFG whose resonant wavelength, i.e., grating pitch, can be changed by adjusting the twist rate of the helical fiber. The H-LPFG inscribed in a standard SMF could be used to generate orbital angular momentum (OAM) modes, i.e., OAM+1 mode, with a purity of 91% and a conversion efficiency of 87% within a large wavelength range from more than the cutoff wavelength of an SMF, which is highly advantageous to all-fiber optical communications based on the OAM mode-division multiplexing technique.
