High-sensitivity MZI strain sensor with separation of cladding mode field and strain concentration area

Area of Science:

• Optical fiber sensing
• Interferometry
• Strain measurement

Background:

• Traditional Mach-Zehnder interferometer (MZI) strain sensors face limitations in sensitivity.
• Effective refractive index changes in cladding modes during strain can reduce sensor performance.

Purpose of the Study:

• To propose and demonstrate a novel wave structure MZI strain sensor (Wavy-MZI).
• To enhance strain sensitivity by spatially separating strain concentration and cladding mode offset areas.

Main Methods:

• Design of a Wavy-MZI utilizing a unique wave structure.
• Experimental characterization of the sensor's strain sensitivity.
• Analysis of effective refractive index changes in core and cladding modes.

Main Results:

• The Wavy-MZI successfully concentrates strain on the inner wave structure.
• Cladding mode fields are offset to the outer wave structure, experiencing minimal strain.
• Achieved a high strain sensitivity of up to 166.64 pm/µε.

Conclusions:

• The Wavy-MZI design significantly improves strain sensitivity compared to conventional MZI sensors.
• This sensor architecture shows great potential for precise weak strain detection applications.
• The spatial separation strategy effectively mitigates performance degradation due to strain-induced refractive index changes.