A high reading rate fiber Bragg grating sensor system using a high-speed swept light source based on fiber vibrations

We propose a fiber Bragg grating (FBG) sensor array system using a high-speed swept light source. The light source is an external cavity semiconductor laser using an optical fiber coupling with a Littrow-mounted grating spectroscope, where the fiber end is vibrated in the cantilever bending mode using a piezoelectric transducer. The incident angle to the grating is scanned at an ultrasonic frequency, and the output wavelength is swept according to the vibration displacement amplitude. The maximum sweep rate of 172 kHz was achieved for the sweep range of 70 nm. In this paper, the light source is used for high-speed and high sensitivity FBG sensor interrogation. First, to test the operation of the proposed FBG sensor, the center wavelength variation due to temperature shift is measured in water. Second, we experimentally demonstrate the measurements of dynamic strain oscillating at 10 and 28 kHz. The observation of high frequency vibrations is achieved with a sufficient sampling rate.