Widely tunable and ultrasensitive leaky-guided multimode fiber interferometer based on refractive-index-matched...

Area of Science:

• Fiber Optic Sensors
• Interferometry
• Nanomaterials

Background:

• Leaky-guided multimode fiber interferometers (MMFIs) offer potential for sensitive measurements.
• Achieving high sensitivity often requires complex fabrication or operation.
• Refractive index-matched coupling is a key mechanism for enhancing sensor performance.

Purpose of the Study:

• To develop a simple, widely tunable, and ultrasensitive sensor.
• To demonstrate the effectiveness of refractive-index-matched coupling in MMFIs.
• To quantify the sensor's response to temperature and refractive index variations.

Main Methods:

• Fabrication of a leaky-guided multimode fiber interferometer (MMFI).
• Utilizing a cladding material with a specific dispersion profile for index-matched coupling.
• Operating the MMFI under conditions of refractive-index-matched coupling at a single wavelength.
• Measuring the sensor's response to changes in temperature (T) and refractive index (RI).

Main Results:

• Achieved a narrow bandwidth and high extinction ratio (>25 dB) coupling wavelength dip.
• Demonstrated effective tuning of the wavelength dip with temperature and RI variations.
• Observed an extremely high tuning efficiency for temperature (50 nm/°C).
• Recorded excellent sensitivity to refractive index (113,500 nm/RI unit).

Conclusions:

• The proposed MMFI sensor is simple, tunable, and ultrasensitive.
• Refractive-index-matched coupling significantly enhances sensing performance.
• The sensor shows great potential for precise environmental monitoring and detection applications.