An FPGA-based demodulation system for fiber Bragg grating sensing

Abstract

ABSTRACT This paper introduces the principle of fiber Bragg grating (FBG) sensor, designs and realizes a compact wavelength demodulation system for FBG sens ing using a Fabry-Perot (F-P) filter. FPGA is adopted as a main controller to control a D/A converter to produce a sawtooth wave for driving the F-P filter, and to design the data acquisition circuit for collecting the output signals of photoelectric detector. The collected data is processed after transmitting to PC through the data transmission circuit, and then the demodulation of FBG wavelength is completed finally. This compact FBG wavelength demodulation system is expected to have wide applications in on-line monitoring of electric power equipment and large structures. Keywords: fiber Bragg grating, F-P filter, electrical power equipment, on-line mon itoring, grating sensing, wavelength demodulation, Gaussian fitting, FPGA 1. INTRODUCTION Rapid advances in optics and electronics have created a large number of optic and electronic components with high performance, such as optical fiber tunable filters, high-sensitivity detectors, digital signal processors, and field programmable gate arrays (FPGAs), over the past years. Meanwhile, a variety of optical fiber sensors for use in different applications, including optical fiber current sensors, optical gyroscopes and optical fiber vibration sensors, have been developed by exploiting low-cost, high-performance optic and electronic components. In particular, fiber Bragg gratings (FBGs)-based sensors have been widely accepted by engineers since they have uniq ue characteristics such as resistance to electromagnetic interference, multiplexing capability and mechanical durability that are extremely attractive for a variety of industrial applications, including on-line monitoring of electric power equipment