Measurement and monitoring of temperature, humidity and strain variation are very requested in great fields and areas such as structural health monitoring (SHM) systems. Currently, the use of fiber Bragg grating sensors (FBGS) is very recommended in SHM systems due to the specifications of these sensors. In this paper, we present the theory of Bragg sensor, therefore we try to measure the effic...

A novel configuration of an interferometric device, based on a full-cycle full (100%) coupler structure, loaded with a Bragg grating symmetrically placed into the uniform coupler waist, is proposed for use as an optical add–drop multiplexer (OADM) with simultaneously optimized add and drop actions. A general method for designing a suitable Bragg grating for optimal inscription in to the uniform...

In this paper, we present strain monitoring of a filament wound composite tank using fiber Bragg grating sensors during hydrostatic pressurization. 20 fiber Bragg grating (FBG) sensors and 20 strain gauges were attached on the domes and cylinder of the composite tank. A wavelength-swept fiber laser (WSFL) was used as a light source to supply high signal power. From the experimental results, it ...

Recently, a novel holographic diffraction grating made of polymer slices alternated to homogeneous films of nematic liquid crystal (POLICRYPS) was realized. We study the optical performance of the POLICRYPS gratings by both numerical simulations and experiments. Characterization of the grating at normal and conical reading mount are performed. The diffraction efficiency depends strongly on the ...

Introduction Recent studies have shown that Fibre Bragg Gratings are well suited to studying the mechanical behaviour of composites [1]. A Fibre Bragg Grating is a small segment of optical fibre with a core of germanium doped silica which gives a periodic and permanent perturbation of the refractive index. An FBG acts like a selective wavelength mirror, reflecting a particular wavelength (Fig. ...

We report the implementation of a low-cost high-resolution WDM interrogation system operating around 800nm region with bandwidth up to 60 nm and resolution of 13 pm by utilising a tilted fibre Bragg grating as an out-coupling device and a CCD-array detector. The system has been evaluated for interrogating fibre Bragg grating based strain, temperature sensors, giving sensitivities of 0.6 pm/με a...

In this work, the performance of five different fiber optic sensors at cryogenic temperatures has been analyzed. A photonic crystal fiber Fabry-Pérot interferometer, two Sagnac interferometers, a commercial fiber Bragg grating (FBG), and a π-phase shifted fiber Bragg grating interrogated in a random distributed feedback fiber laser have been studied. Their sensitivities and resolutions as senso...

Structural health monitoring of composite structures may be accomplished by measuring strains with embedded optical fibre sensors. In this paper, we present the performance of Bragg grating sensors, which are imbedded into a carbon composite laminate and them bonded to the structure in analyse. The paper will briefly discuss the results and compare them with a free fibre Bragg grating bonded in...

A high power polarization maintaining femtosecond Tm-doped fiber laser system is demonstrated. A chirped fiber Bragg grating with normal dispersion was used to compensate the anomalous dispersion from the regular fiber in the 2 µm seed oscillator to generate mode locked pulses with a pulse repetition rate of 30.84 MHz. After chirped pulse amplification, an amplified power of 78 W was obtained. ...

A carbohydrate-based biosensor was prepared by functionalization of the surface of an etched fiber Bragg grating with a glucopyranosyl-siloxane conjugate. Functionalization of the surface with the conjugate resulted in a Bragg grating shift of 24 pm. This shift in the refractive index is consistent with a theoretical shift calculated assuming monolayer coverage of the glucose conjugate on the s...