Controlling light's helicity at the source: orbital angular momentum states from lasers.

Area of Science:

• Optics and Photonics
• Laser Physics

Background:

• Optical modes carrying orbital angular momentum (OAM) are typically generated externally to lasers.
• There is a growing demand for integrated laser systems capable of producing OAM modes.
• Generating OAM modes directly from lasers is difficult due to symmetry and helicity requirements.

Approach:

• This article reviews advancements in direct OAM mode generation from lasers since 1992.
• It covers a range of laser platforms, including gas and solid-state lasers.
• The review encompasses bulk and integrated on-chip solutions, as well as generic devices.

Key Points:

• Progress has been made in overcoming the challenges of direct OAM generation.
• Diverse methods have been developed for various laser systems.
• On-demand generation of both scalar and vector OAM modes is now achievable.

Conclusions:

• Direct laser-based OAM mode generation has significantly advanced.
• Integrated and on-chip solutions are becoming increasingly viable.
• Future work will likely focus on refining these methods for broader applications.