Three-dimensional control of optical waveguide fabrication in silicon

Area of Science:

• Materials Science
• Photonics
• Nanotechnology

Background:

• Silicon photonics is crucial for optical communication and integrated circuits.
• Precise control over waveguide dimensions is essential for advanced photonic devices.
• Existing fabrication methods may lack the resolution or 3D control required for complex structures.

Purpose of the Study:

• To develop a direct-write fabrication technique for 3D silicon waveguides.
• To demonstrate precise control over waveguide dimensions using proton beam irradiation.
• To characterize the optical properties of fabricated silicon waveguides.

Main Methods:

• Utilized a focused 250 keV proton beam for direct-write irradiation of silicon.
• Employed selective slowing of porous silicon formation during anodization.
• Investigated the effect of ion dose on etch rate and waveguide dimensions.
• Measured propagation losses for TE and TM polarizations at 1550 nm.

Main Results:

• Achieved 3D control over waveguide fabrication in silicon.
• Demonstrated dose-dependent control of core dimensions (width 2.5-3.5 µm, height 1.5-2.6 µm).
• Fabricated silicon waveguides with porous silicon cladding.
• Measured propagation losses of 6.7 dB/cm (TE) and 6.8 dB/cm (TM) at 1550 nm.

Conclusions:

• The proton beam direct-write technique offers high spatial resolution for 3D silicon waveguide fabrication.
• This method enables the production of 3D silicon waveguide tapers with controlled profiles.
• The technique shows promise for creating complex silicon photonic integrated circuits.