SOI-based parallel-ring microresonator for simultaneous sensing of refractive index and temperature

Area of Science:

• Photonics and Sensing Technology
• Optical Microsystems
• Nanophotonics

Background:

• Microring resonators are sensitive to changes in their surrounding environment.
• Simultaneous sensing of multiple parameters is crucial for advanced applications.
• Existing sensors often lack the ability to differentiate between various environmental factors.

Purpose of the Study:

• To propose and demonstrate a new microring resonator structure for simultaneous refractive index (RI) and temperature sensing.
• To evaluate the sensing performance and accuracy of the proposed device.
• To explore the sensor's response to analyte thickness.

Main Methods:

• Design of a microring resonator with two parallel-coupled rings of different widths and two straight waveguides.
• Theoretical analysis using characteristic matrix to demonstrate simultaneous measurement capability.
• Simulation of sensor response to changes in RI, temperature, and analyte thickness.

Main Results:

• Achieved RI sensitivities of 141.54 nm/RIU and 73.85 nm/RIU.
• Achieved temperature sensitivities of 40 pm/K and 46.25 pm/K.
• Demonstrated low measurement errors for both RI (±2.19×10⁻⁴) and temperature (±0.69 K).
• Observed a redshift in resonance wavelength with increasing analyte thickness, indicating sensitivity to thickness.

Conclusions:

• The proposed microring resonator enables simultaneous and accurate measurement of RI and temperature.
• The sensor exhibits high sensitivity and low error margins.
• Its simple structure, small footprint, and ease of fabrication make it suitable for environmental, biological, and medical sensing.