Fiber Bragg grating (FBG) sensors have limitations in measuring high and extreme temperatures because general FBG are made of silica fiber, which at can interfere with the mechanical performance materials. In this paper, we propose an S-FBG (Sapphire Grating) sensor is resistant to environmental influences temperatures. By developing measure temperatures, it found that has sensitivity, every 10...

We present here a new class of multi-channel Fiber Bragg grating (FBG), which provides the characteristics of channelized dispersion but does so with only a single reflection band. An FBG of this type can provide pure phase control of the spectral waveform of optical pulses without introducing any deleterious insertion-loss-variation. We anticipate that this new class of FBG will find some appl...

In this paper, we present a Fiber-Bragg-Grating-based temperature sensor. The technique employs heterodyne detection using two Fiber Bragg Gratings. One of the gratings is used as a reference (local oscillator) and the second as a sensing arm. This sensor uses a Folded Mach-Zehnder interferometer. As the temperature changes, the Bragg wavelength of the FBG shifts. The heterodyne detection is us...

A novel linearized interrogation method is presented for a Fourier domain mode-locked (FDML) fiber Bragg grating (FBG) sensor system. In a high speed regime over several tens of kHz modulations, a sinusoidal wave is available to scan the center wavelength of an FDML wavelength-swept laser, instead of a conventional triangular wave. However, sinusoidal wave modulation suffers from an exaggerated...

A new type of optical fiber underwater acoustic sensor (hydrophone) constructed with two fiber Bragg gratings (FBG) and a self-demodulation ethod is presented in this paper. Unlike other FBG sensors which have separate sensing and demodulating elements, this FBG hydrophone has nly a single structure for both sensing and demodulating using a pair of matched FBGs. The cylindrical structure of the...

Conventional closed-bore MRI scanners preclude direct “hands-on” device manipulation. There is a critical need for methods to quickly, accurately and easily manipulate instruments within closed MRI systems. Specifically, catheter, probe, and needle interventions can benefit from optical systems which measure tool positions and forces in real-time. During such procedures, it is useful to track a...

Experimental result of a full scale-steel frame with a smart active control system under shaking table test has been carried out in this paper. Newly, the concept of smart structure has been broached to the extent of structure control. The NEURO-FBG control system, which is composed of both neural networks and fiber Bragg grating sensors, has been theoretically analyzed and simulated to effecti...

This paper deals with a group velocity dispersion issue and a peak reflectivity issue in a non-uniform fiber Bragg gratings (FBG) due to an arbitrary refractive index profile along the length of grating. The paper shows that by using more complicated refractive index profile one can significantly reduce the group velocity dispersion and side lobes intensity and that in main lobe the bandwidth o...

A fiber Bragg grating (FBG) sensor with heat resistance was produced via a point microfabrication technique using a femtosecond pulse laser. The FBG sensor was reinforced by weaving with a carbon fiber tape. As a result, both high strength and a structure for mounting the sensor were readily incorporated. In a high-temperature tolerance evaluation of the FBG sensor, the temperature and strain w...

A fiber Bragg grating- (FBG-) based fiber-ring laser that utilizes the transmitted light of the FBG as self-injection feedback for single-longitudinal-mode (SLM) oscillation is proposed and demonstrated. This laser is simply constructed by means of feeding back the transmitted light of the FBG and is coupled into the main ring cavity through an optical coupler. The self-injection feedback is th...