Real-time measurement system for overlapping reflection signals of fiber Bragg gratings using high-speed wavelength-swept laser

We propose a real-time measurement system that prevents overlapping reflection signals in fiber Bragg gratings (FBGs). The combines wavelength-swept laser using Fourier domain mode-locking (FDML) and buffer stage with three optical paths to obtain high-speed rate of 304.2 kHz. Systems lasers are affected by the propagation time (delay) fiber. delay causes problems such as inaccurate measurements, difficulty distinguishing FBG signals, signals. To prevent these problems, we introduce method for pulse modulation switch. This allows correction delays extracting identifying only signal at specific wavelength. By all FBGs, can be determined. Accordingly, devise uses switch shade light wavelength region one from laser. suppresses other FBGs extracted demodulated. proposed bidirectional forward backward scans laser, shaded demodulated either scanning direction. demonstrate three-buffered FDML simultaneously measure strain or vibration installed arbitrary distances.