Optical frequency domain reflectometry based fiber Bragg grating vibration sensor array using sinusoidal current modulation of laser diodes

We present multipoint vibration sensing using fiber Bragg gratings and optical frequency domain refrectometry (OFDR). In OFDR based method, the maximum number of arrayed sensor can be few thousands and the measurement time is determined by wavelength scanning rate of a light source. In our sensor system, a laser diode is used as a wavelength scanning light source. Lasing wavelength of a laser diode can be modulated by changging its injection current. The injection current can be precisely modulated at high frequency up to 1 MHz using a laser-diode controller and wavelength scanning can be then easily achieved with a laser diode.