Optical fiber sensing device and method

An optical fiber sensing device comprising:

• a light source for outputting continuous light;
• an optical coupler for branching the continuous light;
• a reference interferometer, into which continuous light branched by the optical coupler is injected, for producing a predetermined difference τref in propagation delay time in the continuous light;
• a sensor interferometer, into which continuous light branched by the optical coupler is injected, including a plurality of connected Mach-Zehnder interferometers for producing, in the continuous light, differences in propagation delay time that correspond to integer multiples of the predetermined difference τref in propagation delay time and are different from each other, the Mach-Zehnder interferometers having unilateral optical paths functioning as sensor units;
• and
• a signal processing unit for performing signal processing by using a light reception signal I(t) which is obtained by receiving light transmitting through the sensor interferometer and a reference signal Iref-1 (t) which is obtained by receiving light transmitting through the reference interferometer,
• wherein the signal processing unit
• calculates a reference signal Iref-j (t) corresponding to a j-th (j is a natural number) sensor unit of the sensor units by using the reference signal Iref-1 (t),
• calculates a cross-correlation Rj between the light reception signal I(t) and the reference signal Iref-j (t), and
• detects a change in the j-th sensor unit by using a change in the cross-correlation Rj.