Abstract

Laguerre–Gaussian beams with a nonzero azimuthal index are known to carry orbital angular momentum (OAM), and are routinely created external to laser cavities. The few reports of obtaining such beams from laser cavities suffer from inconclusive evidence of the real electromagnetic field. In this Letter we revisit this question and show that an observed doughnut beam from a laser cavity may not be a pure Laguerre–Gaussian azimuthal mode but can be an incoherent sum of petal modes, which do not carry OAM. We point out the requirements for future analysis of such fields from laser resonators.

© 2014 Optical Society of America

Generation of a vector doughnut beam from an internal mirror He–Ne laser

Sunil Vyas, Yuichi Kozawa, and Shunichi Sato
Opt. Lett. 39(7) 2080-2082 (2014)

Revisiting the which-way experiment with twisted light beams

Lixiang Chen, Wuhong Zhang, Kai Cai, Yuanying Zhang, and Qianqian Qi
Opt. Lett. 39(20) 5897-5900 (2014)

Creation of galaxy-shaped vortex relief structures in azo-polymers with petal-like beams

Arata Tomita, Adam Vallés, Katsuhiko Miyamoto, and Takashige Omatsu
Opt. Express 31(17) 27868-27879 (2023)

Divide and structure: generating and interswitching orthogonal eigenstates of complementary petal beams using a π-shifted Sagnac interferometer

Watson Ly and Ilya Golub
Appl. Opt. 63(8) 1991-1994 (2024)

Angular self-reconstruction of petal-like beams

Igor A. Litvin, Liesl Burger, and Andrew Forbes
Opt. Lett. 38(17) 3363-3365 (2013)