Advanced fabrication of polymer waveguide interferometric sensor utilizing interconnected holey fibers

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Sensor Technology

Background:

• Fiber-optic sensors are crucial for various monitoring applications.
• Fabricating reliable polymer-based fiber-optic sensors presents challenges in achieving uniform filling and high visibility.
• Existing methods often result in suboptimal performance due to incomplete filling or low signal-to-noise ratios.

Purpose of the Study:

• To propose a universally applicable method for fabricating fiber-optic polymer sensors.
• To enhance the performance of polymer Fabry-Perot interferometers for sensing applications.
• To demonstrate a novel approach for creating interconnected in-fiber microchannels for sensor fabrication.

Main Methods:

• Splicing hollow-core fibers (HCFs) with dual-hole fibers (DHF) or photonic crystal fibers (PCF) to create microchannels.
• Utilizing ultraviolet-induced polymerization to form a polymer Fabry-Perot interferometer within the HCF.
• Enhancing interference visibility with a refractive-index-modulated polymer cap.

Main Results:

• Successful fabrication of polymer Fabry-Perot interferometers with optimized interference spectra.
• Achieved a signal-to-noise ratio of 56.8 dB for ultrasonic wave detection, more than double that of partially filled sensors.
• Demonstrated low temperature (230.2 pm/°C) and humidity (93.7 pm/%RH) sensitivity due to the hermetically-sealed structure.

Conclusions:

• The proposed method offers a robust and versatile approach for fabricating high-performance fiber-optic polymer sensors.
• Interconnected holey fibers enable uniform polymer waveguide dimensions and increased spectrum visibility.
• The developed sensor is suitable for diverse microstructure-matched optical fiber applications, particularly for ultrasonic wave detection.