A Fiber Bragg Grating (FBG) sensor demodulation system of matched Bragg gating with a simple structure is studied. The cantilever is designed by using acryl glass, and the wavelength's linear tuning of FBG is operated by tuning the cantilever of acryl glass. The sensor signal of Real-time detect is detected by using an oscilloscope after the optical sensor signal enters the photoelectric detector. Demodulation operation of matched-gating is achieved. Wavelength resolution of 2.33pm is obtained. The advantages of this demodulation system is simple structure, electromagnetic interference resistance, high wavelength resolution and high rate of cost performance, so it has a great application prospect.
A smart temperature sensor is performed based on the high birefringence (HB) fiber loop mirror. The sensing can be achieved by simply detecting the light intensity, utilizing a single mode laser diode (LD) as the source. In the range of 25°C-35°C, the resolution and linear regression are 0.05°C and 0.9986, respectively. The sensor can be employed to precise temperature measurement and the range can expand further when selecting shorter HB fiber in the loop mirror.
A high-sensitivity fiber Bragg grating (FBG) pressure sensor has been designed and studied. Confining some gas inside a glass cylinder with a close glass piston which can move smoothly along the cylinder, and sticking two ends of a fiber Bragg grating on the outer side of the cylinder and piston respectively. The variation of the external pressure results in the change of the tension that the fiber grating is subjected to and then the pressure can be measured by the measurement of the Bragg wavelength of the FBG. The pressure sensitivity coefficient is up to -0.7676/MPa, which is about 3.88×10<sup>5</sup> times the value of bare fiber Bragg gratings, the highest sensitivity ever reported. The sensor can be used to potential applications in the measurement of air pressure, hydraulic pressure and vibration in the range of low pressure.
A TDM FBG sensor system with CCD detection was presented for a serial FBG array. Four FBGs were multiplexed and a device based on NOLM technique was adopted for the separation of the pulses. Computer simulation shows that the system provides high sensitivity which is the main factor for a practical FBG sensor.