Fabry-Perot interferometers for highly-sensitive multi-point relative humidity sensing based on Vernier effect and...

Area of Science:

• Fiber Optic Sensors
• Interferometry
• Materials Science

Background:

• Relative humidity (RH) monitoring is crucial across various industries.
• Existing RH sensors often lack high sensitivity or multiplexing capabilities.
• Fabry-Perot interferometers (FPI) offer a platform for sensitive measurements.

Purpose of the Study:

• To develop and demonstrate a highly sensitive RH sensor.
• To leverage the Vernier effect for enhanced humidity sensitivity.
• To implement a digital signal processing (DSP) algorithm for demodulation and multi-point sensing.

Main Methods:

• Fabrication of an FPI sensor by splicing hollow core Bragg fiber (HCBF) with single mode fiber (SMF).
• Functionalization of the HCBF end with a chitosan and ultraviolet optical adhesive (UVOA) composite film.
• Utilizing the Vernier effect generated by reflection beams for improved sensitivity.
• Developing and verifying a DSP algorithm for spectrum demodulation.

Main Results:

• The proposed sensor demonstrated a high sensitivity of 1.45 nm/% RH within the 45%-90% RH range.
• The Vernier effect significantly enhanced the sensor's humidity sensitivity.
• The DSP algorithm was successfully applied for spectrum processing and verification.

Conclusions:

• The developed FPI-based RH sensor offers high sensitivity, compact size, and multiplexing capability.
• The sensor is a promising candidate for advanced RH monitoring applications.
• The proposed DSP algorithm has potential applications in other Vernier effect-based sensors.