Highly sensitive RI and temperature sensor based on an asymmetric fiber coupler

Area of Science:

• Photonics and Optical Sensing
• Fiber Optic Sensors
• Material Science

Background:

• Refractive index (RI) and temperature sensing are crucial for various scientific and industrial applications.
• Existing fiber optic sensors often face limitations in sensitivity and simultaneous measurement capabilities.
• Asymmetric fiber couplers (AFCs) offer a promising platform for enhanced optical sensing due to their unique light-coupling properties.

Purpose of the Study:

• To propose and demonstrate a novel, highly sensitive sensor for simultaneous refractive index (RI) and temperature measurement.
• To investigate the sensing performance of an asymmetric fiber coupler (AFC) near its dispersion turning point (DTP).
• To explore the potential of packaging the AFC with polydimethylsiloxane (PDMS) for improved temperature sensing.

Main Methods:

• Fabrication of an asymmetric fiber coupler (AFC) via weak fusion of a pre-stretched single-mode fiber and a few-mode fiber.
• Characterization of the AFC sensor's response to changes in refractive index (RI) near the dispersion turning point (DTP).
• Packaging the AFC sensor with polydimethylsiloxane (PDMS) to evaluate its temperature sensing capabilities.

Main Results:

• Achieved ultra-high RI sensitivity of -10,662.4 nm/RIU within the RI range of 1.31-1.35.
• Demonstrated a temperature sensitivity of 11.44 nm/°C when the AFC was packaged with PDMS.
• The sensor exhibited high sensitivity for both RI and temperature measurements.

Conclusions:

• The proposed asymmetric fiber coupler (AFC) sensor offers a highly sensitive platform for simultaneous RI and temperature monitoring.
• The sensor's performance near the dispersion turning point (DTP) enables ultra-sensitive RI detection.
• Potential applications include chemical monitoring, biochemical detection, and clinical diagnostics.