Fully-automated optimization of grating couplers.

Area of Science:

• Photonics
• Nanophotonics
• Integrated Optics

Background:

• Grating couplers are essential for fiber-to-chip communication.
• Current design methods often require manual input and optimization.
• Developing versatile and efficient grating couplers is crucial for advanced photonic integrated circuits.

Purpose of the Study:

• To present a fully automated, gradient-based algorithm for designing 1D grating couplers.
• To demonstrate the algorithm's capability in creating diverse grating coupler functionalities.
• To achieve high efficiency and simplified fabrication for fiber-to-chip interfaces.

Main Methods:

• A gradient-based optimization algorithm was employed for de novo grating coupler design.
• The algorithm operates without human intervention, including initial condition selection.
• Various device geometries and functionalities were explored using the developed algorithm.

Main Results:

• The algorithm successfully designed efficient grating couplers with multiple functionalities.
• Achieved designs include single-polarization, polarization-insensitive, and wavelength-demultiplexing couplers.
• A specific fiber-to-chip blazed grating achieved <0.2 dB insertion loss with single-etch fabrication.

Conclusions:

• The gradient-based algorithm offers a powerful, automated approach to grating coupler design.
• This method enables the creation of complex, high-performance photonic devices.
• The demonstrated single-etch blazed grating represents a significant advancement in efficient fiber-to-chip coupling.