Refractive index sensor based on a polymer fiber directional coupler for low index sensing

Area of Science:

• Photonics and Sensing
• Optical Fiber Technology
• Microstructured Polymer Optical Fibers

Background:

• Refractive index sensing is crucial for various applications, including chemical analysis and biological detection.
• Existing sensors often face limitations in sensitivity and detection limits, especially for low refractive index analytes.
• Microstructured polymer optical fibers offer unique platforms for integrated optical devices.

Purpose of the Study:

• To propose, analyze, and demonstrate a novel refractive index sensor with enhanced sensitivity and a low detection limit.
• To investigate the sensor's performance for low refractive index fluids.
• To explore the sensor's potential for surface-localized measurements relevant to biosensing.

Main Methods:

• Design and numerical analysis of a directional coupler in a single microstructured polymer optical fiber.
• Experimental fabrication and characterization of the proposed sensor.
• Optimization of the sensor architecture for sensitivity and detection limit.

Main Results:

• Demonstrated a novel sensor based on a directional coupler within a microstructured polymer optical fiber.
• Achieved a sensitivity exceeding 1.4 × 10^3 nm/RIU (refractive index unit).
• Simulations indicate a detection limit of approximately 2 × 10^-6 RIU, with potential for surface-based sensing.

Conclusions:

• The developed sensor offers high sensitivity and a low detection limit for refractive index measurements.
• The device is suitable for sensing low refractive index fluids and shows promise for biosensing applications.
• The microstructured polymer optical fiber platform enables advanced integrated optical sensing functionalities.