Robust in-fiber spatial interferometer using multicore fiber for vibration detection.

Area of Science:

• Fiber optics
• Optical sensing
• Interferometry

Background:

• Vibration sensing is crucial in various applications.
• Existing fiber optic sensors often require complex fabrication.
• There is a need for compact, robust, and highly sensitive vibration sensors.

Purpose of the Study:

• To demonstrate a novel in-fiber spatially integrated Michelson interferometer.
• To utilize weakly coupled multicore fiber (MCF) for vibration sensing.
• To achieve a compact, high-sensitivity, and temperature-insensitive vibration sensor.

Main Methods:

• Constructed a Michelson interferometer using two cores of an MCF.
• Utilized cleaved fiber ends for Fresnel reflection and a fan-in coupler for light coupling.
• Interrogated phase changes via reflection power variations using a narrow linewidth laser and analyzed with fast Fourier transform (FFT).

Main Results:

• Achieved vibration sensing with differential strain variation between MCF cores.
• Demonstrated a broad vibration frequency response range up to 12 kHz.
• Sensor performance was independent of core pair selection and showed high sensitivity and temperature insensitivity.

Conclusions:

• The proposed in-fiber integrated spatial interferometer is a novel and effective vibration sensor.
• The sensor offers ultra-compact size, high mechanical strength, and requires no special fiber processing.
• This technology presents a promising solution for advanced vibration monitoring applications.