Hybrid Fabry-Perot interferometer for simultaneous liquid refractive index and temperature measurement

Area of Science:

• Optoelectronics
• Fiber optics
• Sensor technology

Background:

• Accurate simultaneous measurement of liquid refractive index (RI) and temperature is crucial for various scientific and industrial applications.
• Existing sensors often face limitations in sensitivity, spatial resolution, or simultaneous measurement capabilities.

Purpose of the Study:

• To propose and demonstrate a compact, high-sensitivity fiber-optic sensor for simultaneous liquid RI and temperature sensing.
• To achieve high spatial resolution for precise bio/chemical sensing applications.

Main Methods:

• Fabrication of a fiber-tip sensor by inserting a capillary tube segment between single-mode fibers (SMFs).
• Formation of two cascaded Fabry-Perot interferometers (FPIs) within the fiber structure.
• Utilizing the intensity and shift of resonant wavelengths in the reflection spectrum for simultaneous RI and temperature determination.

Main Results:

• Demonstrated simultaneous sensing of liquid RI and temperature with high sensitivity.
• Achieved the highest reported RI sensitivity of ~216.37 dB/RIU at an RI value of 1.30.
• The sensor exhibits a compact size (<400 μm) leading to high spatial resolution.

Conclusions:

• The proposed fiber-tip sensor enables accurate and simultaneous measurement of liquid RI and temperature.
• The sensor's high sensitivity and spatial resolution make it highly promising for advanced bio/chemical sensing.
• This compact device offers a robust solution for precision sensing applications.