High-speed wavelength interrogation system based on crossed HiBi-FLMs for array FBGs

Abstract

A novel ultrafast wavelength interrogation system for array fiber Bragg gratings (FBGs) has been proposed and experimentally demonstrated, the operation principle is based on pulsed optical source (POS) combined with edge-filtering method and time-division multiplexing (TDM) technique. Thanks to the Gaussian-shape nature and numerous passband channels of the HiBi-FLM transmission, the simultaneous interrogation of array wavelength-division multiplexing (WDM) FBGs can be realized by employing crossed HiBi-FLMs scheme. The HiBi-FLM can provide an individual edge filter for each WDM-FBG and map the FBG reflection spectra into corresponding optical intensity, thus realizing the simultaneous interrogation of multiple WDM-FBGs. The interrogation speed of the proposed system is as high as 200 kHz, which can be further improved to hundreds of megahertz (MHz) by increasing the repetition rate of the POS, the response speed of the photodetector (PD), and the sampling rate of field programmable gate array (FPGA), as well as reducing the pulse width and the lengths of the delay lines. The proposed wavelength interrogation system features high speed, outstanding multiplexing capability, large dynamic range and simple configuration, thus providing a promising solution for various applications, such as quasi-distributed sensing, high-speed communication, medical treatment and the monitoring of ultrafast dynamic phenomena (e.g., molecular dynamics sensing and aircraft engine diagnostics).