Polarization-Interference-Based Fiber Vibration Sensor Incorporating Polarization-Diversity Loop Structure

• Published in: IEEE sensors journal Vol. 16; no. 7; pp. 1949 - 1955
• Main Authors: Park, Kyongsoo, Kim, Young Suk, Jo, Songhyun, Lee, Yong Wook
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.04.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Diversity reception; Fibers; Frequency measurement; interference; Interferometers; Optical fiber sensors; optical polarization; Phase shift; Polarization; Sensors; Strain; Temperature sensors; Vibration; Vibration measurement; Vibrations; optical polarization; interference; vibration measurement; Polarization-diversity loop; optical fiber sensors
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2015.2504492

We demonstrate a polarization-interference-based fiber vibration sensor by incorporating a Sagnac interferometer based on a polarization-diversity loop structure composed of a polarization beam splitter, polarization-maintaining photonic crystal fiber, and polarization controllers. A laser diode and a photodetector were used to implement a high-speed intensity-based sensor. By using a piezoelectric transducer, we performed single frequency vibration measurement over 1-3000 Hz, resulting in a cutoff frequency of <inline-formula> <tex-math notation="LaTeX">\sim 2100 </tex-math></inline-formula> Hz, a phase shift per unit length and unit strain of <inline-formula> <tex-math notation="LaTeX">\sim 3.48 </tex-math></inline-formula> mrad/(<inline-formula> <tex-math notation="LaTeX">\mu \varepsilon \cdot {\mathrm{ m}} </tex-math></inline-formula>), and a minimum detectable strain perturbation of <inline-formula> <tex-math notation="LaTeX">\sim 0.46~\text{n}\varepsilon </tex-math></inline-formula>/Hz<inline-formula> <tex-math notation="LaTeX">^{\mathrm {1/2}} </tex-math></inline-formula> at 2000 Hz. Naturally, damped vibration response was also investigated using a metal cantilever, and the relationship between the sensor output and applied impulse was analyzed.