A sensitivity-enhanced refractive index sensor using a single-mode thin-core fiber incorporating an abrupt taper

Area of Science:

• Optoelectronics
• Fiber Optics
• Sensor Technology

Background:

• Refractive index (RI) sensing is crucial in various scientific and industrial fields.
• Existing fiber-optic sensors often face limitations in sensitivity and fabrication complexity.

Purpose of the Study:

• To propose and experimentally demonstrate a sensitivity-enhanced fiber-optic refractive index sensor.
• To utilize a tapered thin-core fiber for improved sensing performance.

Main Methods:

• Fabrication of the sensor head by splicing a tapered thin-core fiber (TCF) between single-mode fibers (SMFs).
• Excitation of cladding modes at the SMF-TCF interface, leading to interference with the core mode (inter-modal interferometer - IMI).
• Utilizing an abrupt taper created via electric-arc heating for enhanced sensitivity.

Main Results:

• The sensor demonstrated a high refractive index sensitivity of 0.591 nm per 1% change in surrounding RI using a glycerol-water mixture.
• The fabrication process involves simple fiber splicing and tapering, achievable with a commercial fiber fusion splicer.

Conclusions:

• The proposed fiber-optic RI sensor offers a simple structure, low cost, and ease of fabrication.
• The sensor exhibits high sensitivity, making it suitable for various RI sensing applications.