Suspended silicon waveguides for long-wave infrared wavelengths

Area of Science:

• Photonics
• Materials Science
• Integrated Optics

Background:

• Silicon photonics is a leading technology for integrated optical circuits.
• Existing silicon waveguides face limitations in mid-infrared wavelengths due to higher propagation losses.
• There is a need for low-loss waveguide platforms for mid-infrared applications.

Purpose of the Study:

• To demonstrate suspended silicon waveguides operating at a mid-infrared wavelength (7.67 μm).
• To achieve propagation losses comparable to exotic materials in silicon waveguides.
• To investigate the performance of waveguide bends and s-bends in this new platform.

Main Methods:

• Fabrication of suspended silicon waveguide cores.
• Utilizing sub-wavelength gratings for lateral optical confinement.
• Employing wet etching with hydrofluoric acid to remove the buried oxide layer.
• Characterization of propagation loss and waveguide bend performance.

Main Results:

• Achieved suspended silicon waveguides operating at 7.67 μm.
• Demonstrated a low propagation loss of 3.1±0.3 dB/cm.
• Showcased low-loss performance for waveguide bends and s-bends.
• Loss is comparable to platforms using more exotic materials.

Conclusions:

• Suspended silicon waveguides offer a promising low-loss platform for mid-infrared photonics.
• This technology can potentially replace exotic materials in certain mid-infrared applications.
• The demonstrated fabrication method and performance pave the way for advanced integrated photonic devices in the mid-infrared spectrum.