Weak fiber grating demodulator based on distributed feedback laser array

A weak fiber grating demodulator based on the distributed feedback laser array (DFB-LA) was proposed used for the large-capacity ultra-weak fiber grating sensor network. This article describes the overall design, DFB-LA-based tunable narrow linewidth pulse light source module, and control demodulation process in detail. After design, the narrow linewidth tunable light source module composed of DFB-LA can realize nanosecond laser pulse output with a wide tuning range of 30nm. A prototype of a weak fiber grating (W-FBG) demodulator was developed, and a sensor demodulation test was carried out with an ultra-weak fiber grating with a reflectivity of -30dBm. The test results show that the system is stable. The prototype achieves a wavelength measurement range of 27nm and a resolution of 1.4pm. The measured W-FBG wavelength-temperature coefficient is 11.88pm/degrees C and the temperature resolution is 0.1 degrees C.