Photonic contact thermometry based on 3 µm thick silicon cascaded ring resonators

Area of Science:

• Photonics
• Optical Sensing
• Materials Science

Background:

• Accurate temperature measurement is crucial across scientific and industrial applications.
• Existing temperature sensors face limitations in sensitivity, operational range, or material compatibility.
• Photonic sensors offer potential advantages due to their inherent properties like high resolution and immunity to electromagnetic interference.

Purpose of the Study:

• To demonstrate a novel photonic temperature sensor.
• To leverage cascaded ring resonators (CRRs) on a silicon-on-insulator (SOI) platform for enhanced temperature sensing.
• To evaluate the sensor's performance, including sensitivity, operational range, and stability.

Main Methods:

• Fabrication of a photonic sensor chip using a 3 µm thick silicon-on-insulator (SOI) platform.
• Integration of three cascaded ring resonators (CRRs) for expanded free spectral range (FSR).
• Characterization of the sensor's temperature response using edge-coupled fiber packaging over a specific temperature range.

Main Results:

• The CRR-based sensor achieved an expanded FSR of 23 nm, enabling a wider operational temperature range.
• The sensor demonstrated a high temperature sensitivity of 85 pm K⁻¹ with a low uncertainty of 16.1 mK.
• The thick SOI platform provided low propagation loss (<0.1 dB cm⁻¹), negligible polarization dependence, and high-power handling (>10 mW).

Conclusions:

• The developed photonic temperature sensor offers a promising solution for precise contact thermometry.
• The use of cascaded ring resonators and a thick SOI platform significantly enhances sensor performance.
• This technology contributes to advancements in temperature measurement, aligning with the redefined kelvin scale.