Photonic temperature and wavelength metrology by spectral pattern recognition

Area of Science:

• Photonics
• Optical Engineering
• Metrology

Background:

• Accurate temperature measurement is crucial in various scientific and industrial applications.
• Wavelength/frequency combs are essential tools for precise optical measurements and calibrations.
• Silicon photonics offers a scalable platform for integrated optical devices.

Purpose of the Study:

• To develop a novel photonic thermometer based on spectral pattern recognition in a silicon waveguide ring resonator.
• To generate calibrated wavelength combs for thermometry and optical referencing.
• To achieve high accuracy in temperature measurement and wavelength calibration.

Main Methods:

• Utilizing a silicon waveguide ring resonator to generate two interleaving TE and TM spectral combs.
• Employing spectral pattern recognition to uniquely identify temperature based on the spectral resonance pattern.
• Implementing two temperature retrieval methods: set-point locking and a spectral correlation algorithm.
• Using an on-chip micro-heater for precise temperature tuning and calibration.

Main Results:

• Demonstrated temperature measurement by recognizing unique spectral patterns.
• Achieved accurate wavelength calibration reference with 5 pm accuracy over an 80 nm range.
• Developed a spectral correlation algorithm for continuous temperature determination to 50 mK accuracy.
• Extended the correlation method to correct for light source wavelength calibration errors.

Conclusions:

• The silicon ring resonator with spectral pattern recognition provides a robust method for photonic thermometry.
• The system offers simultaneous temperature sensing and wavelength calibration capabilities.
• Accuracy is fundamentally limited by the ring resonator's linewidth and quality factor.