Ultrasensitive ultrasound detection using an intracavity phase-shifted fiber Bragg grating in a self-injection-locked diode laser

Yupeng Zhu, Lingling Hu, Zigeng Liu, Ming Han

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

We report a high-sensitivity fiber-optic ultrasonic sensor system using a self-injection-locked distributed-feedback (DFB) diode laser where a π-phase-shifted fiber Bragg grating (πFBG) serves as both the locking resonator and the sensing element in a fiber ring feedback loop. By controlling the delay time of the feedback light through a fiber stretcher, the laser wavelength is locked to an external cavity mode on the spectral slope of the πFBG, and the ultrasound-induced wavelength shifts of the πFBG are converted to laser intensity variation. The ultrasonic sensing scheme simplifies the feedback control because the self-injection locking automatically pulls the laser wavelength to the πFBG resonant wavelength. In addition, it improves the detection sensitivity because the frequency noise of the DFB laser is drastically reduced. We show that the sensor system achieves a strain sensitivity of 78 f ε∕Hz12 at around 200 kHz.

Original languageEnglish (US)
Pages (from-to)5525-5528
Number of pages4
JournalOptics Letters
Volume44
Issue number22
DOIs
StatePublished - Nov 15 2019

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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