Micro-ring resonator-assisted photothermal spectroscopy with integrated pump beam

Area of Science:

• Photonics
• Spectroscopy
• Chemical Sensing

Background:

• Photothermal spectroscopy (PTS) offers high sensitivity for gas detection.
• Traditional PTS systems often require complex alignment of discrete optical components, limiting miniaturization and robustness.

Purpose of the Study:

• To demonstrate a compact, on-chip photothermal spectroscopy (PTS) system with integrated pump beam delivery.
• To develop a scalable pathway for robust, miniaturized, and high-sensitivity gas sensors.

Main Methods:

• Utilized a silicon nitride (SiN) micro-ring resonator (MRR) as the refractive-index transducer.
• Employed a SU-8 waveguide for direct pump beam delivery to the sensing region.
• Integrated pump and probe beams for monitoring resonance shifts in the MRR.

Main Results:

• Achieved a minimum limit of detection (LOD) of 95 ppm for water vapor.
• Demonstrated a linear response to varying gas concentrations.
• Eliminated the need for time-consuming alignment of discrete optical components.

Conclusions:

• The integrated on-chip PTS system offers a scalable solution for miniaturized, high-sensitivity gas sensing.
• Combining CMOS-compatible photonic integration with advanced packaging techniques enhances sensor robustness.
• This approach paves the way for next-generation portable and efficient gas detection devices.