Optical-Fiber Microsphere-Based Temperature Sensors with ZnO ALD Coating-Comparative Study

Area of Science:

• Optoelectronics
• Materials Science
• Sensor Technology

Background:

• Fiber-optic sensors offer remote and robust temperature monitoring capabilities.
• Atomic Layer Deposition (ALD) provides precise control over thin film coatings for enhanced sensor performance.
• Microsphere resonators are sensitive to external environmental changes, making them suitable for sensing applications.

Purpose of the Study:

• To investigate the metrological properties of microsphere-based fiber-optic sensors coated with ZnO using Atomic Layer Deposition (ALD).
• To evaluate the performance of sensors with varying ZnO coating thicknesses (100 nm and 200 nm) for temperature measurements.
• To determine the sensitivity and linearity of the developed sensors within a specific temperature range.

Main Methods:

• Fabrication of microsphere-based fiber-optic sensors with ZnO ALD coatings of 100 nm and 200 nm.
• Characterization of sensor performance over a temperature range of 100°C to 300°C with 10°C increments.
• Utilizing interferometric signals to monitor microsphere integrity and analyzing reflected signal spectrum shift and optical power for temperature sensing.

Main Results:

• Both 100 nm and 200 nm ZnO coated sensors exhibited excellent linearity with R² coefficients over 0.99.
• The sensor with 100 nm ZnO coating showed sensitivities of 19 pm/°C (spectrum shift) and 11.4 nW/°C (optical power).
• The sensor with 200 nm ZnO coating demonstrated a sensitivity of 103.5 nW/°C (optical power).

Conclusions:

• Microsphere fiber-optic sensors with ZnO ALD coatings are effective for accurate temperature measurements.
• The ZnO coating thickness influences the sensing mechanism and sensitivity of the fiber-optic sensor.
• The developed sensors show significant potential for high-precision temperature monitoring applications.