Distributed fiber optic sensing with enhanced sensitivity based on microwave-photonic Vernier effect

Area of Science:

• Optoelectronics
• Microwave Photonics
• Sensor Technology

Background:

• The Vernier effect is a known method for enhancing sensor sensitivity.
• Single-point optical fiber sensors utilizing the Vernier effect have been previously developed.
• Distributed sensing offers advantages over single-point measurements but often faces sensitivity limitations.

Purpose of the Study:

• To demonstrate, for the first time, a distributed optical fiber sensor enhanced by the Vernier effect.
• To leverage microwave photonics for improved sensitivity in distributed sensing.
• To explore the tunability of sensitivity amplification in this novel sensor system.

Main Methods:

• Fabrication of a distributed sensor using an array of cascaded Fabry-Perot interferometers (FPIs) along an optical fiber.
• Interrogation of the FPI array using an optical carrier-based microwave interferometry (OCMI) system.
• Generation of the Vernier effect by superimposing the interferograms of sensing FPIs with a reference FPI.

Main Results:

• Successful reconstruction and superposition of interferograms to generate the Vernier effect.
• Significant improvement in measurement sensitivity of the distributed sensing FPIs.
• Demonstration of sensitivity-enhanced distributed sensing capability using a direct modulation OCMI system.

Conclusions:

• The proposed distributed optical fiber sensor effectively utilizes the Vernier effect for sensitivity enhancement.
• The sensitivity amplification factor is adjustable by controlling the optical length difference between sensing and reference FPIs.
• This work presents a promising advancement in distributed sensing technology with tunable, high sensitivity.