Germanium-on-SOI waveguides for mid-infrared wavelengths.

Area of Science:

• Photonics
• Materials Science
• Optoelectronics

Background:

• Mid-infrared (mid-IR) photonics is crucial for sensing and spectroscopy.
• Germanium-on-Silicon-on-Insulator (Ge-on-SOI) offers potential for mid-IR applications due to its optical properties.

Purpose of the Study:

• To develop and characterize Germanium-on-SOI (Ge-on-SOI) strip waveguides for mid-infrared (mid-IR) wavelengths.
• To assess propagation losses and transparency of these novel waveguides.

Main Methods:

• Fabrication of Ge-on-SOI strip waveguides with varying Germanium (Ge) core thicknesses (0.85 μm and 2 μm) on a Silicon-on-Insulator (SOI) substrate.
• Measurement of propagation loss using the Fabry-Perot method with temperature tuning.
• Assessment of waveguide transparency up to 3.82 μm.

Main Results:

• Achieved a minimum propagation loss of approximately 8 dB/cm for 0.85 μm thick Ge core waveguides.
• Demonstrated waveguide transparency up to at least 3.82 μm.
• Characterized waveguides with varying widths and Ge thicknesses.

Conclusions:

• Ge-on-SOI waveguides are a viable platform for mid-infrared applications.
• The developed waveguides exhibit promising low loss and broad transparency in the mid-IR spectrum.
• Further optimization could lead to enhanced performance for integrated mid-IR photonic devices.