FPGA-Based High-Speed Optical Fiber Sensor Based on Multitone-Mixing Interferometry

We report a real-time high-speed fiber Bragg grating (FBG) interrogator based on a fiber-optic interferometer. The signal processing is performed by using a low-cost fieldprogrammable gate array (FPGA) system, which is programed to implement a phase-generated carrier (PGC) demodulation algorithm with multitone mixing (MTM) to provide distortionfree signals with high tolerance to modulation depth variations and light intensity fluctuations. The system can stream data at rates up to 1 MS/s and allows multiplexed processing up to two channels. Experimental results show simultaneous measurements of two FBGs, one of which was actuated at frequencies up to 100 kHz. The system features a 3-dB bandwidth of 280 kHz, and a dynamic wavelength resolution of 4.7 fm/Hz1/2. We also demonstrate a strong reduction of distortion using the MTM approach with respect to the standard technique. Finally, we study the origin of the noise, demonstrating a reduction in common noise sources by using one of the FBGs as a reference. The system can measure FBGs centered at any position within the spectral band of the source, is polarization-independent, and is easily scalable to more than two measurement channels from the same interferometer.

Automated summary

We report on the development of a real-time high-speed fiber Bragg grating interrogator based on a fiber-optic interferometer. The system utilizes a low-cost FPGA system for signal processing, implementing a PGC demodulation algorithm with MTM to provide distortion-free signals with high tolerance to modulation depth variations and light intensity fluctuations. The system can achieve data streaming at rates up to 1 MS/s and supports multiplexed processing of up to two channels. Experimental results demonstrate simultaneous measurements of two FBGs, one of which can be actuated at frequencies up to 100 kHz. The system features a wide bandwidth and dynamic wavelength resolution, and exhibits reduced distortion compared to the standard technique through the use of the MTM approach.