Compact optical fiber curvature sensor based on concatenating two tapers.

Area of Science:

• Optoelectronics
• Fiber Optics Sensors
• Nanophotonics

Background:

• Optical fiber sensors offer remote and real-time monitoring capabilities.
• Curvature sensing is crucial for structural health monitoring and medical applications.
• Existing sensors often face limitations in sensitivity, size, or dynamic range.

Purpose of the Study:

• To develop a low-loss, compact, and highly sensitive optical fiber curvature sensor.
• To investigate the sensing mechanism based on cladding mode coupling.
• To analyze the influence of design parameters and environmental factors on sensor performance.

Main Methods:

• Fabrication of a sensor comprising two identical low-loss fused fiber tapers in tandem.
• Analysis of spectral transmission changes under varying curvature conditions.
• Experimental evaluation of dynamic range, sensitivity, and environmental effects (temperature, refractive index).

Main Results:

• A distinct interference pattern emerges in the transmitted spectrum upon bending the fiber.
• The visibility of interference fringes increases with curvature, reaching near unity.
• The sensor's dynamic range is tailorable by adjusting taper diameter and separation distance.

Conclusions:

• The proposed fused fiber taper sensor demonstrates high sensitivity and a tunable dynamic range for curvature measurement.
• The device exhibits a robust sensing mechanism relying on cladding mode interference.
• Further characterization confirms the sensor's potential for practical applications, with considerations for environmental influences.