Simultaneous strain and temperature fiber grating laser sensor based on radio-frequency measurement

Area of Science:

• Fiber optic sensing
• Photonics
• Instrumentation

Background:

• Accurate simultaneous strain and temperature measurement is crucial for structural health monitoring and industrial applications.
• Existing fiber optic sensors often require complex interrogation systems or are limited in their measurement capabilities.

Purpose of the Study:

• To propose and demonstrate a novel, compact fiber optic sensor for simultaneous strain and temperature measurement.
• To utilize radio-frequency (RF) beat notes from concatenated lasers for sensing applications.
• To offer an interrogation method that is simpler and more cost-effective than traditional wavelength-based detection.

Main Methods:

• Fabrication of a sensing head comprising two concatenated ultra-short distributed Bragg reflector (DLR) lasers.
• Operation of the DBR lasers in single longitudinal mode with two polarization modes.
• Generation and analysis of two RF polarization mode beat notes.
• Correlation of RF beat note frequency shifts with applied strain and temperature variations.

Main Results:

• Successful demonstration of a simultaneous strain and temperature fiber optic sensor with an 18 mm sensing head.
• Two distinct RF beat notes were generated, exhibiting differential responses to strain and temperature.
• Simultaneous measurement was achieved through RF signal analysis, validating the sensor's performance.

Conclusions:

• The proposed fiber optic sensor enables accurate, simultaneous strain and temperature measurement.
• The RF-based interrogation method simplifies the sensing system and reduces costs.
• This technology presents a promising solution for advanced sensing applications requiring robust and cost-effective instrumentation.