A Novel MZI Fiber Sensor with Enhanced Curvature and Strain Sensitivity Based on Four-Core Fiber

Area of Science:

• Optoelectronics
• Fiber Optic Sensors
• Interferometry

Background:

• Mach-Zehnder interferometers (MZIs) are widely used for sensing applications.
• Enhancing the sensitivity of fiber optic sensors is crucial for precise measurements.
• Novel fiber configurations are needed to improve sensor performance.

Purpose of the Study:

• To develop a high-sensitivity curvature and strain fiber optic sensor.
• To investigate the sensing performance of a Mach-Zehnder interferometer (MZI) based on no-core fiber (NCF) and four-core fiber (FCF).
• To explore the potential applications of this novel sensor design.

Main Methods:

• Fabrication of the sensor by directly splicing a segment of four-core fiber (FCF) between two segments of no-core fiber (NCF) using an optical fiber fusion splicer.
• Utilizing the multi-path interference characteristics of FCF and the mode excitation properties of NCF.
• Experimental characterization of the sensor's response to varying curvature and strain.

Main Results:

• The sensor demonstrated high sensitivity to curvature, reaching -78.04 dB/m⁻¹ within a range of 0.0104 m⁻¹-0.1515 m⁻¹, with a high linearity of ~0.99.
• The sensor also exhibited significant strain sensitivity, with a maximum of -6.49 pm/με in the range of 0-600 με.
• The proposed NCF-FCF configuration effectively excites higher-order modes, leading to enhanced sensing performance.

Conclusions:

• The developed NCF-FCF based MZI fiber sensor offers high sensitivity for both curvature and strain measurements.
• The sensor's design leverages multi-path interference and higher-order mode excitation for improved performance.
• This sensor shows significant potential for various sensing and measurement applications.