Abstract
We propose and demonstrate an intensity-demodulated fiber-optic ultrasonic sensor system that can be selfadaptive to large quasi-static background strain perturbations. The sensor system is based on a fiber ring laser (FRL) whose laser cavity includes a pair of fiber Bragg gratings (FBGs). Self-adaptive ultrasonic detection is achieved by a tandem design where the two FBGs are engineered to have differential spectral responses to ultrasonic waves and are installed side-by-side at the same location on a structure. As a result, ultrasonic waves lead to relative spectral shifts of the FBGs and modulations to the cold-cavity loss of the FRL. Ultrasonic waves can then be detected directly from the laser intensity variations in response to the cold-cavity loss modulation. The sensor system is insensitive to quasi-static background strains because they lead to identical responses of the tandem FBGs. Based on the principle, a FRL sensor system was demonstrated and tested for adaptive ultrasonic detection when large static strains as well as dynamic sinusoidal vibrations were applied to the sensor.
Original language | English (US) |
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Pages (from-to) | 4462-4465 |
Number of pages | 4 |
Journal | Optics Letters |
Volume | 39 |
Issue number | 15 |
DOIs | |
State | Published - Aug 1 2014 |
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics