Optical fiber long-period grating sensors.
TL;DR: A novel class of highly sensitive sensors based on long-period fiber gratings that can be implemented with simple and inexpensive demodulation schemes are presented.
Abstract: We present a novel class of highly sensitive sensors based on long-period fiber gratings that can be implemented with simple and inexpensive demodulation schemes. Temperature, strain, and refractive-index resolutions of 0.65 °C, 65.75 μ∈, and 7.69 × 10−5, respectively, are demonstrated for gratings fabricated in standard telecommunication fibers.
Citations
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TL;DR: In this paper, the authors review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings and intragrating sensing concepts.
Abstract: We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors.
3,665 citations
TL;DR: In this paper, the authors reviewed recent research on fiber optic long-period gratings (LPGs) with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction.
Abstract: Recent research on fibre optic long-period gratings (LPGs) is reviewed with emphasis placed upon the characteristics of LPGs that make them attractive for applications in sensing strain, temperature, bend radius and external index of refraction. The prospect of the development of multi-parameter sensors, capable of simultaneously monitoring a number of these measurands will be discussed.
1,203 citations
TL;DR: In-fibre Bragg grating (FBG) sensors are one of the most exciting developments in the field of optical fiber sensors in recent years as discussed by the authors, and significant progress has been made in applications to strain and temperature measurements.
Abstract: In-fibre Bragg grating (FBG) sensors are one of the most exciting developments in the field of optical fibre sensors in recent years. Compared with conventional fibre-optic sensors, FBG sensors have a number of distinguishing advantages. Significant progress has been made in applications to strain and temperature measurements. FBG sensors prove to be one of the most promising candidates for fibre-optic smart structures. This article presents a comprehensive and systematic overview of FBG sensor technology regarding many aspects including sensing principles, properties, fabrication, interrogation and multiplexing of FBG sensors. It is anticipated that FBG sensor systems will be commercialized and widely applied in practice in the near future due to the maturity of economical production of FBGs and the availability of cost effective interrogation and multiplexing techniques.
1,170 citations
TL;DR: The goal of this study is to review the fundamental structures and chemistries of wood and wood-derived materials, which are essential for a wide range of existing and new enabling technologies.
Abstract: With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much more to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interes...
1,031 citations
TL;DR: In this article, the transmission of a mode guided by the core of an optical fiber through an ultraviolet-induced fiber grating when substantial coupling to cladding modes occurs is analyzed both experimentally and theoretically.
Abstract: The transmission of a mode guided by the core of an optical fiber through an ultraviolet-induced fiber grating when substantial coupling to cladding modes occurs is analyzed both experimentally and theoretically. A straightforward theory is presented that is based on the calculation of the modes of a three-layer step-index fiber geometry and on multimode coupled-mode theory that accurately models the measured transmission in gratings that support both counterpropagating (short-period) and co-propagating (long-period) interactions. These cladding-mode resonance filters promise unique applications for spectral filtering and sensing.
894 citations
References
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01 Jan 1996
TL;DR: In this paper, a new class of long-period fiber gratings that can be used as in-fiber, low-loss, band-rejection filters is presented.
Abstract: We present a new class of long-period fiber gratings that can be used as in-fiber, low-loss, band-rejection filters. Photoinduced periodic structures written in the core of standard communication-grade fibers couple light from the fundamental guided mode to forward propagating cladding modes and act as spectrally selective loss elements with insertion losses act as backreflections <-80 dB, polarization-mode-dispersions <0.01 ps and polarization-dependent-losses <0.02 dB.
1,772 citations
TL;DR: In this paper, a new class of long-period fiber gratings that can be used as in-fiber, low-loss, band-rejection filters is presented.
Abstract: We present a new class of long-period fiber gratings that can be used as in-fiber, low-loss, band-rejection filters. Photoinduced periodic structures written in the core of standard communication-grade fibers couple light from the fundamental guided mode to forward propagating cladding modes and act as spectrally selective loss elements with insertion losses act as backreflections <-80 dB, polarization-mode-dispersions <0.01 ps and polarization-dependent-losses <0.02 dB.
1,696 citations
TL;DR: Simple formulas and functions for the fiber parameters are presented as a help for practical design work that considers the propagation constant, mode delay, the cladding field depth, and the power distribution in the fiber cross section.
Abstract: Thin glass fibers imbedded into a glass cladding of slightly lower refractive index represent a promising medium for optical communication. This article presents simple formulas and functions for the fiber parameters as a help for practical design work. It considers the propagation constant, mode delay, the cladding field depth, and the power distribution in the fiber cross section. Plots vs frequency of these parameters are given for 70 modes
1,506 citations
TL;DR: In this article, photoinducing index gratings within the fiber core were used to construct a mode convertor with conversion efficiencies of over 75% and simple spectral response curves with one or two peaks.
Abstract: LP01 ↔ LP02 mode convertors have been fabricated by photoinducing index gratings within the fibre core by means of internally or externally applied light fields. The mode convertors have conversion efficiencies of over 75% and simple spectral response curves with one or two peaks. The mode conversion linewidths range from 0.2 to 10 nm.
67 citations