Optical fiber axial micro-displacement sensor based on Mach-Zehnder interferometer

Area of Science:

• Fiber optic sensing
• Optical interferometry
• Micro-displacement measurement

Background:

• Accurate measurement of micro-displacements is crucial in various scientific and industrial applications.
• Existing fiber optic sensors often lack sufficient sensitivity or are complex to fabricate.
• Mach-Zehnder interferometers offer a potential platform for high-sensitivity sensing.

Purpose of the Study:

• To propose and demonstrate a novel fiber axial micro-displacement sensor based on a Mach-Zehnder interferometer (MZI).
• To investigate the relationship between axial micro-displacement and the MZI transmission spectrum.
• To evaluate the sensor's sensitivity and temperature characteristics.

Main Methods:

• Fabrication of an MZI using a bowknot-type taper (BTT) and a fiber core-offset between two single mode fibers (SMFs).
• Characterization of the sensor's response to axial micro-displacement by analyzing its transmission spectrum.
• Testing the sensor's performance with different interferometer arm lengths (12, 18, 24, and 30 mm).
• Theoretical simulations of energy distributions within the interferometer.

Main Results:

• The proposed MZI sensor demonstrated high sensitivity to axial micro-displacement, with a maximum of -0.385 dB/μm for an arm length of 18 mm.
• The sensor exhibited low temperature errors, ranging from -0.036 °C to -0.056 dB/°C.
• The achieved sensitivity is approximately 150 times higher than that of currently available similar axial micro-displacement sensors.

Conclusions:

• The developed MZI-based fiber sensor is highly sensitive and accurate for measuring axial micro-displacements.
• The sensor design, utilizing a BTT and core-offset, offers a promising approach for advanced displacement sensing.
• This technology has the potential to surpass existing methods in terms of sensitivity and performance.