Abstract
We theoretically and experimentally investigate a locking method for a fiber-optic acoustic emission (AE) sensor system based on a π-phase-shifted fiber Bragg grating (π-FBG) and a distributed-feedback diode laser. The π-FBG features a narrow notch in the middle of the reflection spectrum for high-sensitivity AE detection. The investigated locking method generates a signal that is proportional to the second derivative of this spectral notch, which is used as the error signal. The laser wavelength is automatically locked to one of the zero-crossing points of the error signal, which corresponds to the maximum slope of the selected side of the spectral notch. With the laser locked to the maximum slope, the optimal sensitivity for AE detection is obtained. We also show that the locking point is immune to low-frequency variations of the output power of the laser.
| Original language | English (US) |
|---|---|
| Article number | 8464070 |
| Pages (from-to) | 9257-9262 |
| Number of pages | 6 |
| Journal | IEEE Sensors Journal |
| Volume | 18 |
| Issue number | 22 |
| DOIs | |
| State | Published - Nov 15 2018 |
Keywords
- Optical fiber sensors
- acoustic emission
- distributed feedback lasers
- fiber Bragg gratings
- laser wavelength locking
ASJC Scopus subject areas
- Instrumentation
- Electrical and Electronic Engineering