Highly sensitive temperature sensor based on an ultra-compact Mach-Zehnder interferometer with side-opened channels.

Area of Science:

• Fiber optics
• Optical sensing
• Nanotechnology

Background:

• Mach-Zehnder interferometers (MZIs) are widely used for sensing applications.
• Microstructured optical fibers (MOFs) offer unique properties for optical device fabrication.
• High thermo-optic coefficient liquids can enhance temperature sensing sensitivity.

Purpose of the Study:

• To demonstrate an ultra-compact and highly sensitive temperature sensor.
• To utilize an in-fiber Mach-Zehnder interferometer (MZI) with side-opened channels for enhanced performance.
• To explore the potential of microstructured optical fibers (MOFs) in temperature sensing.

Main Methods:

• Fabrication of an in-fiber MZI by off-center splicing a MOF between single-mode fibers.
• Drilling side-opened channels into the MOF using a femtosecond laser.
• Infiltration of the MOF air cavity with isopropanol, a liquid with a high thermo-optic coefficient.

Main Results:

• Achieved an ultra-compact MOF-based MZI with a scale of several hundred micrometers.
• Demonstrated a high temperature sensitivity of 3.8 nm/°C with isopropanol infiltration.
• Observed low strain cross-sensitivity of 0.0001 °C/μϵ in the 22°C-34°C range.

Conclusions:

• The developed MOF-based MZI is a competitive fiber sensor for highly sensitive temperature measurements.
• The sensor's compact size and high sensitivity make it suitable for healthcare and consumer electronics.
• The side-opened channel design effectively utilizes liquids with high thermo-optic coefficients for improved sensing.