Current Trends In Short And Long Period Fiber Gratings

In this book the reader will find a collection of chapters written by different experts around the world, describing the current research trends in both short- and long-period fiber grating technology. This work is mainly addressed to researchers already working in this area, but it is also accessible to anyone with a scientific background who desires to have an updated overview of the recent progress in this domain. It will also be valuable to scientist and engineers who have become newly involved in this field. Each chapter is self-contained and can be read independently of the others. This book intends to provide highlights of the current research in this area, showing the recent advances in the field of fiber gratings.

A fiber Bragg grating (FBG) is a type of distributed Bragg reflector constructed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all others. This is achieved by creating a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror. A fiber Bragg grating can therefore be used as an inline optical filter to block certain wavelengths, or as a wavelength-specific reflector. Fiber Bragg gratings are created by "inscribing" or "writing" systematic (periodic or aperiodic) variation of refractive index into the core of a special type of optical fiber using an intense ultraviolet (UV) source such as a UV laser. A long-period fiber grating couples light from a guided mode into forward propagating cladding modes where it is lost due to absorption and scattering. It is an optical fiber structure with the properties periodically varying along the fiber, such that the conditions for the interaction of several copropagating modes are satisfied. The period of such a structure is of the order of a fraction of a millimeter. In contrast to the fiber Bragg gratings, LPFGs couple copropagating modes with close propagation constants; therefore, the period of such a grating can considerably exceed the wavelength of radiation propagating in the fiber. Because the period of an LPFG is much larger than the wavelength, LPFGs are relatively simple to manufacture. Since LPFGs couple copropagating modes, their resonances can only be observed in transmission spectra. Long period grating has a wide variety of applications, including band-rejection filters, gain flattening filter and sensors. Various gratings with complex structures have been designed: gratings combining several LPFGs, LPFGs with superstructures, chirped gratings, and gratings with apodization. Various LPFG-based devices have been developed: filters, sensors, fiber dispersion compensators, etc. This book entitled Current Trends in Short- and Long-period Fiber Gratings emphasizes the current trends in both short- and long-period fiber grating technology. This book intends to provide highlights of the current topics in this area, showing the recent advances in the field of fiber gratings.

This book includes of a compilation of valuable information contributed by distinct veterans from across the globe, elucidating the recent research trends in both short- and long-period fiber grating technology. It is primarily intended for researchers already engaged in this area, but it is also useful for anybody with a scientific background who is interested in an up-to-date analysis of the current growth in this domain. It will also prove to be useful for engineers and scientists who have become recently involved in this field. The aim of this book is to examine the present research in this area, displaying the current progresses in the field of fiber gratings.

In this book the reader will find a collection of chapters written by different research teams, describing different applications of optical fibers for sensing. This work is mainly addressed to researchers already working in this area, but it is also accessible to anyone with a scientific background who desires to have an updated overview of the recent progress in this domain. It will also be valuable to scientists and engineers who have become newly involved in this field. Each chapter is self-contained and can be read independently of the others. This book intends to provide highlights of the current research in this area, showing the recent advances in the field of optical fiber sensing.

This book is a collection of papers that originated as a Special Issue, focused on some recent advances related to fiber Bragg grating-based sensors and systems. Conventionally, this book can be divided into three parts: intelligent systems, new types of sensors, and original interrogators. The intelligent systems presented include evaluation of strain transition properties between cast-in FBGs and cast aluminum during uniaxial straining, multi-point strain measurements on a containment vessel, damage detection methods based on long-gauge FBG for highway bridges, evaluation of a coupled sequential approach for rotorcraft landing simulation, wearable hand modules and real-time tracking algorithms for measuring finger joint angles of different hand sizes, and glaze icing detection of 110 kV composite insulators. New types of sensors are reflected in multi-addressed fiber Bragg structures for microwave–photonic sensor systems, its applications in load-sensing wheel hub bearings, and more complex influence in problems of generation of vortex optical beams based on chiral fiber-optic periodic structures. Original interrogators include research in optical designs with curved detectors for FBG interrogation monitors; demonstration of a filterless, multi-point, and temperature-independent FBG dynamical demodulator using pulse-width modulation; and dual wavelength differential detection of FBG sensors with a pulsed DFB laser.

This book covers most of the damage mechanism in the scope of mechanical engineering and civil engineering. The failure pattern of various materials and structures is mainly discussed. The sub-topics covers fatigue damage, fatigue crack initiation and propagation, life prediction techniques, computational fracture mechanics, dynamic fracture, damage mechanics and assessment, non-destructive test (NDT), concrete failure assessment, failure on soil structures, structural durability and reliability, structural health monitoring, construction damage recovery, and any relevant topics related to failure analysis.

Sponsored by the Alexander von Humbold Stiftung the "Bragfost-Confernce" brings together about 60 outstanding German and Brazilian Scientists to discuss most topical issues in the field of electrical engineering, energy-supply as well as sociological impact of technology. This book presents the most relevant contributions in extended and revised form.

Application of Optical Fiber in Engineering chronicles the recent progress in the research and development of optical fiber technology and examines present and future opportunities by presenting the latest advances on key topics such as birefringence and polarization mode dispersion characteristics, quantum communication, polymer optical fiber grating, optical fiber sensing devices and the Raman fiber laser. All the contributing authors are experts in the field, and this book contains their latest research. This book will provide an invaluable source for researchers, engineers, and advanced students in the field of optical fibers, photonics, optoelectronics, fiber lasers, and sensors.