Realization of efficient metal grating couplers for membrane-based integrated photonics

Area of Science:

• Photonics
• Integrated Optics
• Nanotechnology

Background:

• Grating couplers are essential for light transmission between optical fibers and photonic integrated circuits.
• Existing dielectric gratings face challenges with parasitic light leakage and substrate interference.

Purpose of the Study:

• To fabricate and evaluate a novel buried metal grating coupler.
• To assess its performance advantages over traditional dielectric gratings.

Main Methods:

• Fabrication of a buried metal grating coupler using standard processes.
• Characterization of the device's optical performance, including bandwidth and coupling efficiency.
• Simulations to predict and analyze light leakage and substrate interaction.

Main Results:

• The buried metal grating coupler exhibited a 3 dB bandwidth of 61 nm.
• Achieved a chip-to-fiber coupling efficiency of 54%.
• Simulations indicated significantly reduced parasitic light leakage compared to dielectric gratings.

Conclusions:

• Buried metal gratings offer a high-yield, robust solution for light coupling in photonic devices.
• The device's performance is independent of optical buffer thickness, simplifying integration.
• These gratings are promising for on-wafer testing and dense optical interconnect applications.