Tilted fiber grating accelerometer incorporating an abrupt biconical taper for cladding to core recoupling

Area of Science:

• Photonics and Sensing Technologies
• Fiber Optic Sensors
• Instrumentation and Measurement

Background:

• Fiber-optic sensors offer advantages in harsh environments.
• Microbending-sensitive fiber structures are crucial for accelerometers.
• Existing accelerometers may require complex interrogation methods.

Purpose of the Study:

• To develop a compact, power-referenced fiber-optic accelerometer.
• To utilize a weakly tilted fiber Bragg grating (TFBG) and biconical taper.
• To achieve acceleration measurement through optical power changes.

Main Methods:

• A fiber-optic accelerometer was fabricated using a TFBG and an electric-arc-induced biconical taper.
• The taper recouples cladding modes to the core, enhancing microbending sensitivity.
• Acceleration is measured by monitoring reflected optical power, avoiding wavelength interrogation.
• Bragg resonance serves as a power reference to compensate for light source fluctuations.

Main Results:

• The sensor exhibits a constant linear response with nonlinearity < 1% from DC to 250 Hz.
• The upper frequency limit is tunable by adjusting sensor length.
• The compact sensor head (20-100 mm length, 2 mm diameter) is suitable for embedded detection.
• A polymer-tube package provides stiffness for in-field measurements.

Conclusions:

• A novel, compact, and power-referenced fiber-optic accelerometer has been successfully demonstrated.
• The sensor offers a simple interrogation method and robust performance.
• The design is well-suited for embedded acceleration sensing in various applications.