Temperature-insensitive miniaturized fiber inline Fabry-Perot interferometer for highly sensitive refractive index...

Area of Science:

• Optics and Photonics
• Materials Science
• Sensor Technology

Background:

• Refractive index measurement is crucial for chemical and biological analysis.
• Existing sensors often face limitations in sensitivity, size, or temperature stability.
• Miniaturized optical sensors offer potential for enhanced performance and broader applications.

Purpose of the Study:

• To develop and characterize a miniaturized fiber inline Fabry-Perot interferometer (FPI) for highly sensitive refractive index (RI) measurement.
• To evaluate the sensor's performance in measuring the RI of various liquids and its temperature dependence.
• To assess the suitability of the FPI sensor for chemical and biological sensing applications.

Main Methods:

• Fabrication of an open micro-notch cavity FPI using one-step femtosecond (fs) laser micromachining.
• Testing the FPI sensor for refractive index measurements of isopropanol, acetone, and methanol at room temperature.
• Evaluating the temperature-dependent refractive index of deionized water from 3 to 90 degrees C.

Main Results:

• Achieved a high sensitivity of 1163 nm/RIU for water RI measurement at 1550 nm wavelength.
• Demonstrated a low temperature cross-sensitivity of approximately 1.1x10(-6) RIU/degrees C.
• Observed a linear response across the tested liquid samples and temperature range.

Conclusions:

• The miniaturized FPI sensor offers a highly sensitive and stable platform for refractive index sensing.
• Its all-fiber structure, small size, and low temperature dependence make it attractive for real-time chemical and biological detection.
• The fs laser micromachining fabrication method enables efficient and precise sensor construction.