PLC-AWG-based FBG demodulation system for high-frequency vibration measurement

A fiber Bragg grating (FBG) demodulation system based on arrayed waveguide gratings (AWGs) is proposed. We designed the key parameters of the AWG, prepared the AWG chip based on a silica-on-silicon planar light wave circuit (PLC) platform, and integrated the AWG with a PD array. Eight AWG output channels were selected and the output signals from the photodiode (PD) array was connected to the board with gold wire bonding. The demodulation circuitry consists of transimpedance amplifiers (TIAs), analog-to-digital converters (ADCs), and a main control chip. The signal from the PDs are synchronously captured and amplified and then transmitted at high speed through an Ethernet interface. The total volume of the demodulation system is 200 × 100 × 60 mm³. Experiments show that the wavelength demodulation accuracy of the system is 4.24 pm, the demodulation rate is more than 200 kHz, and the average error of the demodulation acceleration is better than 22.8 mg. The proposed demodulation system can be applied in the field of high-frequency vibration sensing of FBGs.