Extracting the core and cladding contributions to fluorescence and Raman emission in integrated photonic waveguides

Area of Science:

• Integrated Photonics
• Optical Sensing
• Materials Science

Background:

• Minimizing background optical emission is crucial for high-sensitivity integrated photonic platforms.
• Background signals from fluorescence or Raman scattering obscure weak optical signals in sensors.
• Accurate characterization of waveguide performance is essential for sensor development.

Purpose of the Study:

• Introduce a novel parameter-extraction technique to quantify waveguide losses and background generation.
• Separate contributions of waveguide core and cladding to background signals.
• Enable diagnosis and reduction of material-specific propagation loss and background signals.

Main Methods:

• Developed a parameter-extraction technique using standard photonic waveguides.
• No specialized sample preparation or auxiliary test wafers required.
• Experimentally validated the technique on silicon-nitride waveguides from a 300-mm-wafer platform.

Main Results:

• Quantitatively separated waveguide losses and background-generation efficiency.
• Identified individual contributions of core and cladding to background signals.
• Demonstrated correlation between propagation loss and fluorescence, and resolved material-specific Raman spectra differences.

Conclusions:

• The developed technique provides a practical tool for quantifying and diagnosing background signals in photonic waveguides.
• Enables effective development of low-noise and low-loss integrated photonics platforms.
• Facilitates advancements in biosensing, chemical detection, environmental monitoring, and quantum sensing.