Extensible multi-wavelength interrogation method for arbitrary cavities in low-fineness multi-cavity Fabry-Pérot...

Area of Science:

• Fiber optics
• Optical sensing
• Interferometry

Background:

• Low-fineness multi-cavity Fabry-Pérot interferometric (LFMFPI) sensors offer versatile sensing capabilities.
• Interrogating individual cavities within LFMFPI sensors presents challenges, especially for simultaneous multi-parameter measurements.

Purpose of the Study:

• To propose and experimentally demonstrate a novel extensible multi-wavelength (EMW) method for interrogating arbitrary cavities in LFMFPI sensors.
• To enable simultaneous extraction of variations from each cavity in a LFMFPI sensor.

Main Methods:

• Derivation of a theoretical model for LFMFPI sensors with any number of cascaded cavities.
• Development and application of the extensible multi-wavelength (EMW) method for sensor interrogation.
• Experimental validation using LFMFPI sensors under varying temperature and vibration conditions.

Main Results:

• Successful demonstration of the EMW method in both simulations and experiments.
• Accurate extraction of optical path differences (OPD) due to temperature variations (78 nm and 2.95 µm) in two cavities.
• Precise measurement of OPD induced by vibration (amplitude range: 5.891 nm to 38.116 nm).

Conclusions:

• The proposed EMW method provides a feasible approach for interrogating LFMFPI sensors.
• The method allows for simultaneous measurement of parameters within multiple cavities.
• The EMW method shows significant potential for multi-parameter sensing applications, including pressure, vibration, and temperature.