On-Chip Reconfigurable and Ultracompact Silicon Waveguide Mode Converters Based on Nonvolatile Optical Phase Change...

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Efficient higher-order mode sources are crucial for on-chip multimode applications.
• Existing mode converters often lack reconfigurability or efficiency.

Purpose of the Study:

• To propose and demonstrate an on-chip reconfigurable silicon waveguide mode conversion scheme.
• To utilize the nonvolatile and low-loss optical phase change material antimony triselenide (Sb₂Se₃).

Main Methods:

• Embedding a tapered Sb₂Se₃ layer into a silicon waveguide.
• Cladding the structure with graphene and aluminum oxide layers for microheating.
• Utilizing the phase state of Sb₂Se₃ to control mode conversion.

Main Results:

• Achieved reconfigurable TE₀-to-TE₁ mode conversion (and no conversion).
• Demonstrated high conversion efficiency (97.5%), low insertion loss (0.2 dB), and low mode crosstalk (-20.5 dB).
• Device length is only 2.3 μm.

Conclusions:

• The proposed device offers a novel solution for reconfigurable mode conversion in silicon photonics.
• The scheme can be extended to other higher-order mode conversions.
• This technology can serve as fundamental building blocks for on-chip multimode photonics.