Silicon-based horizontal nanoplasmonic slot waveguides for on-chip integration

Area of Science:

• Photonics
• Materials Science
• Nanotechnology

Background:

• Silicon photonics is crucial for integrated circuits.
• Plasmonic waveguides offer miniaturization potential but face propagation loss challenges.
• Integrating plasmonic devices with silicon photonics requires compatible fabrication and low-loss interfaces.

Purpose of the Study:

• To fabricate and characterize horizontal metal/insulator/Si/insulator/metal nanoplasmonic slot waveguides (PWGs) using standard Si-CMOS technology.
• To evaluate the performance of copper-based PWGs (Cu-PWGs) in terms of propagation loss, coupling efficiency, and bending loss.
• To demonstrate the potential for integrating PWGs into existing silicon electronic photonic integrated circuits (Si-EPICs).

Main Methods:

• Fabrication of horizontal metal/insulator/Si/insulator/metal nanoplasmonic slot waveguides (PWGs) using standard Si-CMOS technology.
• Characterization of propagation loss, coupling efficiency, and bending loss for Cu-PWGs.
• Comparison of Cu-PWGs with aluminum-based counterparts.

Main Results:

• Cu-PWGs exhibit low propagation loss (~0.37-0.63 dB/µm) at 1550 nm, approximately 2.6 times lower than Al-PWGs.
• A tapered coupler achieves high coupling efficiency (~0.1-0.4 dB per facet) between PWGs and Si wire waveguides.
• Cu-PWGs demonstrate low bending loss (~0.6-1.0 dB) for a 90° bend, enabling sharp turns.

Conclusions:

• The thin insulator layer is critical for increasing propagation distance and preventing metal diffusion.
• Cu-PWGs fabricated with Si-CMOS technology show promising performance for integrated photonics.
• These results highlight the potential for seamless integration of nanoplasmonic devices into Si-EPICs.