Single- and two-phase flow characterization using optical fiber Bragg gratings (FBGs) is presented. The sensor unit consists of the optical fiber Bragg grating positioned transversely to the flow and fixed in the pipe walls. The hydrodynamic pressure applied by the liquid or air/liquid flow to the optical fiber induces deformation that can be detected by the FBG. Given that the applied pressure...

A sensitivity-improved fiber-optic strain sensor using an etched and regenerated fiber Bragg grating (ER-FBG) suitable for a large range of temperature measurements has been proposed and experimentally demonstrated. The process of chemical etching (from 125 µm to 60 µm) provides regenerated gratings (at a temperature of 680 °C) with a stronger reflective intensity (from 43.7% to 69.8%), togethe...

The measurement of the internal deformations occurring in real-life composite components is a very challenging task, especially for those components that are rather difficult to access. Optical fiber sensors can overcome such a problem, since they can be embedded in the composite materials and serve as in situ sensors. In this article, embedded optical fiber Bragg grating (FBG) sensors are used...

An arrayed waveguide grating (AWG) demodulation integration microsystem is investigated in this study. The system consists of a C-band on-chip LED, a 2 × 2 silicon nanowire-based coupler, a fiber Bragg grating (FBG) array, a 1 × 8 AWG, and a photoelectric detector array. The coupler and AWG are made from silicon-on-insulator wafers using electron beam exposure and response-coupled plasma techno...

We demonstrated a simple interrogation system for multiplexed fiber Bragg grating sensors with high frequency range. A tunable Fabry-Perot filter with narrow free spectral range (FSR) was used to simplify the multiplexing demodulator for FBG vibration sensors. A stabilization controlling unit was also developed for the maintenance of maximum sensitivity of the sensors. In order to verify the pe...

Clamped fiber Bragg grating (FBG) sensors have been widely applied in engineering strain measurements due to their advantages of high flexibility and efficiency. However, due to the existence of the interlayer, the strain measured by the encapsulated FBG sensor is not equal to the strain of the host material, which causes strain measurement errors. In this paper, the strain transfer analysis of...

An optical filter is incorporated in a conventional ultrasound detection system that uses a fiber Bragg grating (FBG) and broadband light source, to demodulate the FBG sensor signal. A novel ultrasound sensing system that does not require an optical filter is presented herein. Ultrasound could be detected via the application of signal processing techniques, such as signal averaging and frequenc...

A novel in-fiber structure for power-referenced refractometry with the capability to measure surrounding refractive index (SRI) as low as 1.33 is proposed and demonstrated. A short optical fiber stub containing a weakly tilted Bragg grating is spliced to another fiber with a large lateral offset. The reflection from this structure occurs in two well-defined wavelength bands, the Bragg reflected...

We propose a novel fiber Bragg grating (FBG) sensor interrogation system using a Raman-based Fourier domain mode locking (FDML) fiber laser for a high speed and a long distance measurement. To improve transmission efficiency of the sensing probe signal over a long distance of 20-km, the residual pump powers are recycled. The external strain change can be measured by detecting the tine interval ...

In wavelength division multiplexed (WDM) optical networks, intraband and/or interband crosstalk plays a major role in limiting practical implementation of an OXC subsystem. Again FIBER BRAGG GRATINGS (FBGs), due to their properties, are emerging as very important elements for both the optical fiber communication and sensing fields. The crosstalk sources are related to the different individual c...