Enhanced refractometer for aqueous solutions based on perfluorinated polymer optical fibres

Area of Science:

• Optical Engineering
• Polymer Science
• Sensor Technology

Background:

• Cyclized Transparent Optical Polymer (CYTOP) fibers are increasingly used for optical structures and parameter detection.
• Optical sensors offer non-invasive and sensitive measurement capabilities.

Purpose of the Study:

• To design, simulate, and manufacture a CYTOP-based sensor for measuring the refractive index of aqueous solutions.
• To achieve high sensitivity and temperature insensitivity for accurate measurements.

Main Methods:

• Utilizing a bent and polished CYTOP fiber to enhance sensitivity.
• Inscribing a diffraction grating on the polished fiber surface using a femtosecond laser.
• Analyzing the interaction between the fiber's optical field and the grating for refractive index detection.

Main Results:

• Achieved high sensitivity in the refractive index range of 1.315–1.333 at 1550 nm wavelength.
• Demonstrated a maximum sensitivity of -208.8 nm/RIU.
• Observed remarkable insensitivity to temperature variations.
• Obtained unique spectral fingerprints for different sensed fluids.

Conclusions:

• The developed CYTOP-based sensor is effective for precise refractive index measurements in aqueous solutions.
• The sensor's high sensitivity, temperature insensitivity, and spectral fingerprinting capabilities make it suitable for various applications.
• This technology advances optical sensing for fluid analysis.