Ultrasensitive temperature sensor and mode converter based on a modal interferometer in a two-mode fiber

Area of Science:

• Optical Fiber Sensing
• Nanophotonics
• Interferometry

Background:

• Modal interferometers in optical fibers offer unique sensing properties.
• Tapered two-mode fibers (TTMF) provide a robust platform for interferometric devices.
• The Vernier-like effect can significantly enhance sensing resolution.

Purpose of the Study:

• To develop an ultrasensitive temperature sensor.
• To create a tunable multi-channel mode converter.
• To leverage isopropanol's properties for enhanced sensing.

Main Methods:

• Fabrication of a modal interferometer using tapered two-mode fiber (TTMF) between single-mode fibers.
• Sealing the TTMF within an isopropanol-filled capillary.
• Utilizing the Vernier-like effect for sensitivity enhancement.
• Characterizing the transmission spectrum for temperature sensing and mode conversion.

Main Results:

• Achieved a high temperature sensitivity of -140.5 nm/°C.
• Demonstrated a sensitivity magnification factor of 58.5 due to the Vernier-like effect.
• Confirmed the device functions as a tunable multi-channel mode converter, converting LP01 to LP11 modes.
• Observed a blue shift in the transmission spectrum with increasing temperature.

Conclusions:

• The isopropanol-sealed modal interferometer is a highly effective ultrasensitive temperature sensor.
• The device serves as a versatile tunable mode converter, adaptable via temperature and mode switching.
• This technology holds promise for advanced optical sensing and signal processing applications.