Fiber Bragg Grating Sensor Multiplexing System Based on the Time- and Wavelength- Division Technique

摘要

A FBG sensor multiplexing system based on the combination of wavelength- and time- division multiplexing technique is proposed. In this paper, A semiconductor optical amplifier (SOA) connected in a ring cavity is used to serve as a gain medium and switch. The sensor array is consisted of four groups of sensors and the nominal wavelength of the sensors in the same group is different. The SOA is driven by a pulse generator which switch on the SOA at different periods, as a switch to select the reflected pulses from a particular group. Using low reflectivity (3%～5%) sensors the number of the groups can achieved 50, the bandwidth of each group used in this system is 40 nm (1525-1565nm), the system permits the interrogation of up to 1000 FBG sensors. With this technique, the FBG sensors system avoid using optical switch to expand channels, it improved the response speed and reduced cost in the application of structural health monitoring where large numbers of sensors are required.