Contents


Preface

In recent years, much effort has been devoted to the study, development, and application of point-to-point fiber sensing for various parameter sensing. Fiber Bragg gratings (FBGs) are key components in the endeavor, usually fabricated using UV laser sources and a phase mask or interferometric techniques. An FBG can be used as a band reject filter; to detect strain, pressure, and temperature; and in telecommunication systems for wavelength selection, among other uses. On the other hand, distributed fiber sensing can monitor the environment along the fiber change based on the Brillouin scattering effect. Distributed Brillouin sensing technique has developed rapidly over the last thirty years. Quite a few investigations on the performance enhancement of Brillouin sensors have been conducted on sensing distance and spatial resolution, paving the way to industrial and commercial applications.

This book presents recent advances in fiber sensing technologies, both in theoretical and real applications, reflecting the cutting-edge technologies and research achievements within these research fields. After a rigorous review process, the editors selected five outstanding chapters from among the submissions for inclusion in this contributor volume. Of these, four are focused on the subject of point-to-point fiber sensing, and the fifth covers distributed fiber sensing. The authors work in

academia and industry in Austria, United States, Korea, and Taiwan.

In Chapter 1, "Introductory Chapter: An Overview of the Methodologies and Applications of Fiber Optic Sensing," the editors briefly address the importance of fiber optic sensing, which may be applied in various fields where optical fiber is used either as a transmission medium or as a sensing head. Point-to-point fiber sensing using fiber Bragg gratings (FBGs) and distributed fiber sensing based on Brillouin scattering effect will be introduced. Some prior works based on either of

In Chapter 2, Fathy Mohamed Mustafa and Mofreh Toba introduce the "Theoretic Study of Cascaded Fiber Bragg Grating." They simulate and analyze the spectral characteristics of the fiber Bragg grating to obtain narrow bandwidth and minimization side lobes in reflectivity. Model equations of cascaded uniform fiber Bragg grating and different cascaded apodization functions are numerically handled and processed via specially cast software to achieve maximum reflectivity, narrow bandwidth without side lobes. For better performance, the proper values for grating length and refractive index modulation must be chosen to achieve maximum

In Chapter 3, "Femtosecond Transient Bragg Gratings" are investigated by Avishay Shamir et al. The authors briefly review the advantages of femtosecond fabrication of fiber Bragg gratings. Then they focus on transient FBGs for optical switching. An experimental result is achieved on generation and characterization of the transient FBGs. A possible mechanism to realize high-power femtosecond laser is introduced. The immunization technique presented here can be used to implement transient

The book consists of the following chapters:

these fiber sensing methodologies are introduced.

reflectivity and narrow bandwidth.
