Demonstration of a refractometric sensor based on an optical micro-fiber three-beam interferometer

Area of Science:

• Optics and Photonics
• Fiber Optic Sensing
• Interferometry

Background:

• Optical micro-fibers exhibit unique waveguiding properties like tunable confinement and strong evanescent fields.
• Micro-fiber based sensors offer miniaturization, high sensitivity, and low power consumption for optical sensing applications.

Purpose of the Study:

• To theoretically and experimentally investigate a novel refractometric sensor utilizing a micro-fiber three-beam interferometer.
• To explore the relationship between sensor sensitivity, evanescent field fraction, and interferometric arm lengths.

Main Methods:

• Development of a micro-fiber three-beam interferometer.
• Theoretical analysis of evanescent field interactions and interferometric principles.
• Experimental validation of the sensor's performance and sensitivity.

Main Results:

• Sensor sensitivity depends on both the evanescent field fraction and the effective lengths of the interferometric arms.
• Significant sensitivity enhancement is achieved when the effective lengths of the interferometric arms are equalized.
• Demonstrated potential for increased refractive index detection sensitivity.

Conclusions:

• The micro-fiber three-beam interferometer represents a promising platform for highly sensitive refractive index sensing.
• Equalizing interferometric arm lengths is a key strategy for maximizing sensor sensitivity.
• This approach holds significant potential for advancing miniaturized fiber optic sensor technology.