Fiber-integrated refractive index sensor based on a diced Fabry-Perot micro-resonator

Area of Science:

• Photonics and Sensor Technology
• Optical Fiber Sensing
• Micro-resonator Fabrication

Background:

• Refractive index sensing is crucial for various applications, including chemical analysis and environmental monitoring.
• Existing fiber-optic sensors often face challenges in sensitivity, selectivity, and ease of fabrication.
• Fabry-Perot interferometers offer a promising platform for high-performance optical sensing.

Purpose of the Study:

• To demonstrate a novel fiber-integrated refractive index sensor based on a Fabry-Perot micro-resonator.
• To evaluate the sensor's performance in measuring refractive indices of sucrose solutions and in air.
• To explore methods for enhancing sensor performance through material coating.

Main Methods:

• Fabrication of a Fabry-Perot micro-resonator using diamond blade dicing of a single-mode step-index fiber.
• Characterization of the sensor's response to refractive index variations of sucrose solutions.
• Measurement of temperature cross-sensitivity.
• Analysis of broadband reflection spectra to determine minimum detectable refractive index changes.
• Investigation of potential performance enhancement via high-index material coating.

Main Results:

• Achieved a high sensitivity of 1160 nm/RIU at a wavelength of 1.55 μm.
• Demonstrated a low temperature cross-sensitivity of less than 10^-7 RIU/°C.
• Accurately measured refractive index steps as small as 10^-5 in solutions.
• Identified potential for significant performance improvement through sidewall coating.

Conclusions:

• The developed fiber-integrated Fabry-Perot micro-resonator sensor offers a simple fabrication method and high performance for refractive index sensing.
• The sensor exhibits excellent sensitivity and temperature stability, suitable for precise measurements.
• Coating the resonator with high-index materials presents a viable strategy for further enhancing sensor capabilities.