Bimodal grating coupler design on SOI technology for mode division multiplexing at 1550 nm

Area of Science:

• Photonics
• Optical Engineering
• Nanotechnology

Background:

• Efficient mode coupling is crucial for integrated photonic devices.
• Two-mode fiber and silicon-on-insulator (SOI) waveguides offer advanced functionalities.
• Simultaneous coupling of multiple modes presents a significant challenge.

Purpose of the Study:

• To investigate simultaneous coupling of LP01x-LP11ax fiber modes and TE0-TE1 SOI waveguide modes.
• To design and optimize a grating coupler for this dual-mode coupling application.
• To evaluate coupling efficiency, compactness, and misalignment tolerance.

Main Methods:

• Utilized simulation and experimental evaluation.
• Designed grating couplers with varying widths (10-15 µm) and vertical profiles.
• Optimized grating period and width for maximum coupling efficiency.

Main Results:

• Identified an optimal design with a 14 µm width and 609 nm grating period.
• Achieved 49% coupling efficiency for LP01x-TE0 modes.
• Achieved 45% coupling efficiency for LP11ax-TE1 modes.

Conclusions:

• Demonstrated successful simultaneous dual-mode coupling between two-mode fiber and SOI waveguides.
• The optimized grating coupler design offers high efficiency and good misalignment tolerance.
• This work advances the development of compact and efficient integrated photonic systems.