Evanescent coupling to silicon waveguides using surface plasmon polaritons

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nanotechnology

Background:

• Surface plasmon polaritons (SPPs) offer unique light-matter interaction properties at optical frequencies.
• Evanescent coupling is crucial for integrating photonic devices with nanoscale structures.
• The Otto configuration provides a method for non-contact excitation of SPPs.

Purpose of the Study:

• To investigate evanescent light coupling into silicon waveguides via SPPs in the Otto configuration.
• To analyze the efficiency of SPP excitation and coupling using specific material and geometric parameters.
• To compare simulation results with experimental measurements for a fabricated device.

Main Methods:

• Utilizing a fused-silica prism, a silver thin film, and a tapered silicon waveguide in the Otto configuration.
• Exciting SPPs with p-polarized light at a 1550 nm wavelength and a 44° plasmonic angle.
• Performing 2D Lumerical FDTD Solutions simulations to model coupling efficiency.
• Fabricating a device on a silicon-on-insulator substrate for experimental validation.

Main Results:

• 2D Lumerical FDTD Solutions simulation predicted a coupling efficiency of 54%.
• Experimental measurements of the fabricated device showed a 10% light transmission for p-polarized light.
• Discrepancies between simulated and experimental results highlight potential areas for optimization.

Conclusions:

• Evanescent light coupling to silicon waveguides using SPPs in the Otto configuration is feasible.
• The study provides insights into the performance limitations and potential of this coupling method.
• Further research is needed to bridge the gap between simulated and experimental efficiencies for practical applications.