Ultra-high-sensitivity refractive index sensor based on dual-microfiber coupler structure with the Vernier effect

Area of Science:

• Photonics and Optical Sensing
• Fiber Optic Sensors
• Metamaterials

Background:

• Refractive index (RI) sensors are crucial for detecting chemical and biological analytes.
• Traditional sensors often lack the required sensitivity for precise measurements.
• Microfiber couplers (MFCs) offer a platform for developing compact optical sensors.

Purpose of the Study:

• To demonstrate a novel, high-sensitivity RI sensor based on the Vernier effect in dual MFCs.
• To investigate the theoretical and experimental sensitivity enhancement using the Vernier effect.
• To explore the potential applications of this sensor in various fields.

Main Methods:

• Fabrication of dual microfiber coupler (MFC) structures with specific dimensions and free spectral range (FSR).
• Theoretical modeling and numerical simulations to predict sensor performance.
• Experimental characterization of the Vernier effect-based sensor for RI sensing.

Main Results:

• Achieved an ultra-high sensitivity of 126,540 nm/RIU using dual MFCs and the Vernier effect.
• Demonstrated a significant sensitivity improvement (several times) compared to single MFC sensors.
• Experimental results showed good agreement with numerical simulations in the RI range of 1.3350 to 1.3455.

Conclusions:

• The proposed all-fiber RI sensor offers ultra-high sensitivity and low cost.
• The Vernier effect in dual MFCs is a promising approach for enhanced optical sensing.
• Potential applications include chemical/biological detection and field measurements.