Diffraction-free orbital angular momentum holography.

Area of Science:

• Optics and Photonics
• Information Technology
• Materials Science

Background:

• Conventional holograms suffer from diffraction, limiting fidelity and detection.
• Existing methods for diffraction-free beams are complex and lack Fourier transform capabilities.
• Holography has potential in data storage, encryption, AI, and 3D displays.

Purpose of the Study:

• To propose a novel approach for diffraction-free holographic displays using an extended depth-of-focus (EDOF) flat lens.
• To demonstrate the capability of maintaining holographic image fidelity over extended distances and through scattering media.
• To explore the use of orbital angular momentum (OAM) for encoding information in diffraction-free beams.

Main Methods:

• Utilized an inverse-designed EDOF lens with a 20 mm depth-of-focus, significantly exceeding conventional lenses.
• Implemented orbital angular momentum (OAM) modes with topological charges from -8 to 8 for holographic image encoding.
• Experimentally validated diffraction-free beam self-healing after occlusion and information preservation through dense fog.

Main Results:

• Achieved a depth-of-focus 14 times greater than conventional lenses, creating an extended spatial-frequency domain (ESFD).
• Demonstrated selectable, diffraction-free OAM-encoded holographic images on a single device.
• Confirmed self-healing properties of OAM beams and their resilience to scattering in dense fog, preserving information where conventional beams failed.

Conclusions:

• The EDOF lens approach enables robust, diffraction-free holographic displays with extended depth-of-field.
• OAM-encoded diffraction-free beams offer a promising solution for high-security optical encryption and advanced optical communication.
• The technology shows potential for applications like optical tweezers and resilient data transmission in challenging environments.