Sensitivity enhanced temperature sensor with serial tapered two-mode fibers based on the Vernier effect

Area of Science:

• Fiber optics sensors
• Optical sensing technologies
• Metrology

Background:

• Traditional temperature sensors often lack the sensitivity required for harsh industrial environments.
• The Vernier effect offers a potential mechanism for enhancing sensor sensitivity.
• Cascaded fiber configurations can be explored to amplify sensing signals.

Purpose of the Study:

• To propose and experimentally demonstrate a sensitivity-enhanced temperature sensor.
• To investigate the performance of cascaded tapered two-mode fibers (TTMFs) for temperature sensing.
• To compare series and parallel TTMF configurations for optimal sensor design.

Main Methods:

• Fabrication of tapered two-mode fibers (TTMFs) with slightly different free spectral ranges (FSRs).
• Cascading two TTMFs in a series configuration.
• Experimental validation of the sensor's performance across a specific temperature range.
• Theoretical analysis of series versus parallel TTMF connections.

Main Results:

• The proposed sensor utilizes the Vernier effect for enhanced temperature sensitivity.
• Series connection of TTMFs demonstrated a higher extinction ratio compared to parallel connection.
• Achieved a high temperature sensitivity of -3.348 nm/°C within the 25°C to 60°C range.
• Observed an 11.3-fold sensitivity enhancement compared to a single TTMF.

Conclusions:

• The cascaded TTMF sensor based on the Vernier effect offers significant sensitivity enhancement.
• Series configuration is recommended for improved extinction ratio in TTMF-based sensors.
• The sensor's high sensitivity, simple manufacturing, and long-distance sensing capabilities make it suitable for applications in oil wells and coal mines.