Practical interrogation scheme for the abrupt taper Mach-Zehnder interferometer refractive index sensor.

Area of Science:

• Optoelectronics
• Fiber optics
• Interferometry

Background:

• Conventional refractive index (RI) sensing systems often rely on expensive broadband light sources and optical spectrum analyzers.
• Mach-Zehnder interferometers (MZIs) are sensitive to changes in the surrounding environment, making them suitable for RI sensing.

Purpose of the Study:

• To design and demonstrate a practical and cost-effective interrogation scheme for a refractive index sensing system based on an abrupt fiber taper Mach-Zehnder interferometer.
• To simplify the system architecture by replacing conventional components with more accessible alternatives.

Main Methods:

• An abrupt fiber taper Mach-Zehnder interferometer sensor was utilized.
• Two single-wavelength laser diodes modulated by a square waveform replaced the broadband light source.
• A simple photodetector (PD) replaced the optical spectrum analyzer for signal detection.
• LabVIEW programming was employed for automatic data acquisition and processing.

Main Results:

• The proposed interrogation scheme was successfully implemented and demonstrated experimentally.
• The system achieved a high sensitivity of 2371 mV/RIU (millivolts per refractive index unit).
• The sensing system exhibited high stability in its measurements.

Conclusions:

• The developed interrogation scheme offers a practical, cost-effective, and easily integrable solution for refractive index sensing.
• The simplified system architecture maintains high sensitivity and stability, making it suitable for various applications.