Generating and synthesizing ultrabroadband twisted light using a compact silicon chip

Area of Science:

• Photonics and Optical Engineering
• Nanotechnology
• Quantum Information Science

Background:

• Manipulation of light's spatial modes is crucial for advanced optical applications.
• Existing methods for generating orbital angular momentum (OAM) modes can be bulky or limited in bandwidth.
• On-chip solutions are needed for compact and versatile OAM mode control.

Purpose of the Study:

• To demonstrate chip-scale generation and synthesization of ultrabroadband OAM modes.
• To utilize a silicon photonics platform for integrated optical mode manipulation.
• To explore applications in optical communications and quantum key distribution.

Main Methods:

• Integrated a subwavelength holographic fork grating onto a silicon waveguide.
• Converted in-plane guided modes to free-space OAM modes.
• Employed dual-sided waveguide inputs for OAM mode synthesization.

Main Results:

• Achieved chip-scale generation and synthesization of ultrabroadband OAM modes.
• Demonstrated favorable wavelength-dependent emission efficiency, offset angle, and purity.
• Validated the performance of the silicon-based OAM generator and synthesizer.

Conclusions:

• The developed chip-scale device offers a compact and efficient solution for OAM mode manipulation.
• This technology holds significant potential for advancements in multidimensional optical communications.
• The OAM generator and synthesizer could be applied to enhance security in quantum key distribution systems.