Orbital angular momentum mode sorting based on a hybrid radial-angular hybrid lens

Area of Science:

• Optics and Photonics
• Quantum Information Science

Background:

• Orbital angular momentum (OAM) modes exhibit a phase distribution exp(jlθ), analogous to plane waves.
• Traditional angular lenses focus OAM beams but suffer from long tails for non-ring beams due to unsatisfied focal conditions.

Purpose of the Study:

• To propose a hybrid radial-angular lens for improved OAM beam focusing and sorting.
• To address the limitations of existing angular lenses for arbitrary beam profiles.

Main Methods:

• Development of a hybrid lens combining angular and radial phase manipulation.
• Implementation of a radially distributed phase to satisfy angular focal conditions for diverse beam parameters.

Main Results:

• The hybrid lens effectively focuses OAM beams by meeting angular focal conditions for arbitrary beam waist and radial distribution.
• Demonstrated efficient discrimination of different OAM modes using the single optical component.
• Achieved a low inter-mode crosstalk of 3.7% for OAM modes with a topological charge difference of 3.

Conclusions:

• The proposed hybrid radial-angular lens significantly enhances OAM mode sorting performance.
• This novel optical component offers an efficient solution for OAM beam manipulation and analysis.