Supermode Bragg grating combined Mach-Zehnder interferometer for temperature-strain discrimination

Area of Science:

• Photonics
• Fiber Optics
• Sensor Technology

Background:

• Integrated optical fiber sensors offer miniaturization and enhanced performance.
• Distinguishing between temperature and strain is crucial for many sensing applications.

Purpose of the Study:

• To develop a compact all-solid photonic bandgap fiber sensor.
• To integrate Mach-Zehnder interference and cladding Bragg grating for dual-parameter sensing.
• To achieve simultaneous discrimination of temperature and axial strain.

Main Methods:

• Fabrication of a compact sensor by integrating Mach-Zehnder interference and cladding Bragg grating in all-solid photonic bandgap fiber.
• Theoretical investigation of the sensing mechanisms.
• Analysis of the distinct responses of interference fringe and supermode grating dip to axial strain and temperature.

Main Results:

• The Bragg grating resonance arises from the coupling of counter-propagating cladding LP01-like supermodes.
• The Mach-Zehnder interference occurs between a LP01-like supermode and LP01 core mode.
• The supermode grating dip exhibits higher sensitivity and opposite direction response to axial strain compared to the interference fringe.
• The interference fringe demonstrates higher temperature sensitivity than the supermode grating dip.

Conclusions:

• The integrated sensor leverages different responses to axial strain and temperature.
• This device enables effective discrimination between temperature and axial strain.
• The compact design and dual-sensing capability offer practical applications in various fields.