Simultaneous refractive index and temperature sensing system realized by hybrid interferometer structures-based...

Area of Science:

• Photonics and Optical Sensing
• Microwave Photonics
• Interferometry

Background:

• Accurate simultaneous measurement of refractive index (RI) and temperature is crucial for various applications.
• Existing sensing methods often face limitations in measurement range or resolution.

Purpose of the Study:

• To propose and experimentally demonstrate a hybrid fiber interferometers-based microwave photonic filter (MPF) for simultaneous RI and temperature sensing.
• To leverage frequency interrogation in the electrical domain for an unlimited measurement range.

Main Methods:

• Utilizing an extrinsic Fabry-Perot interferometer (EFPI) with single-mode fibers (SMFs) for RI sensing.
• Employing a Sagnac interferometer (SI) with polarization-maintaining fiber (PMF) for temperature sensing.
• Tracking dual-passbands of the MPF at different central frequencies for dual-parameter sensing.

Main Results:

• Achieved a refractive index sensitivity of 1197.604 MHz/RIU within the 1.332-1.412 RIU range.
• Obtained a temperature sensitivity of 0.934 MHz/°C in the 20-50 °C range.
• Demonstrated high resolution, ease of fabrication, and good stability.

Conclusions:

• The proposed hybrid fiber interferometer sensor effectively achieves simultaneous RI and temperature sensing.
• The frequency interrogation method offers an unlimited measurement range, surpassing wavelength interrogation.
• The system shows significant potential for applications in biochemical detection, environmental monitoring, and industrial production.