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High-efficiency grating coupler based on fast directional optimization and robust layout strategy in 130 nm CMOS
Optics Letters
|April 1, 2022
Summary
We developed a high-efficiency grating coupler for fiber-to-chip connections using interleaved etching and apodization. This design achieves excellent coupling efficiency without complex structures, simplifying fabrication.
Area of Science:
- Photonics
- Nanotechnology
- Materials Science
Background:
- Fiber-to-chip coupling is crucial for integrated photonic circuits.
- Existing grating couplers often require complex fabrication or additional materials.
- Optimizing coupling efficiency and bandwidth remains a key challenge.
Purpose of the Study:
- To demonstrate a high-efficiency grating coupler for fiber-to-chip coupling.
- To utilize an interleaved etch and apodized structure for enhanced performance.
- To develop a robust and manufacturable grating coupler design.
Main Methods:
- Optimization using the fast directional optimization method for apodization.
- Implementation of a layout strategy with an extended mask to prevent alignment errors in a multi-etch structure.
- Fabrication using a commercial silicon photonics process with a 140 nm minimum feature size.
Main Results:
- Achieved a coupling efficiency of -2.2 dB at 1549 nm wavelength.
- Measured a 3 dB bandwidth of 47 nm.
- Demonstrated fabrication without gold reflectors, subwavelength index matching, or extra material layers.
Conclusions:
- The developed grating coupler offers a high-efficiency and robust solution for fiber-to-chip coupling.
- The design is compatible with standard silicon photonics foundry processes.
- The proposed optimization and fabrication methods are adaptable to foundry design rules.
