Forbes Andrew
School of Physics, University of the Witwatersrand, Private Bag 3, Wits 2050, Johannesburg, South Africa
Philos Trans A Math Phys Eng Sci. 2017 Feb 28;375(2087). doi: 10.1098/rsta.2015.0436.
Optical modes that carry orbital angular momentum (OAM) are routinely produced external to the laser cavity and have found a variety of applications, thus increasing the demand for integrated solutions for their production. Yet such modes are notoriously difficult to produce from lasers due to the strict symmetry requirements for their creation, together with the need to break the degeneracy in helicity. Here, we review the progress made since 1992 in producing such twisted light modes directly at the source, from gas to solid-state lasers, bulk to integrated on-chip solutions, through to generic devices for on-demand OAM in both scalar and vector forms.This article is part of the themed issue 'Optical orbital angular momentum'.
携带轨道角动量（OAM）的光学模式通常在激光腔外部产生，并已得到广泛应用，这使得对其产生的集成解决方案的需求不断增加。然而，由于产生这些模式需要严格的对称性要求，同时还需要打破螺旋度的简并性，因此从激光中产生这些模式非常困难。在这里，我们回顾了自1992年以来在直接从光源产生这种扭曲光模式方面所取得的进展，从气体激光器到固体激光器，从体材料到集成片上解决方案，再到用于按需产生标量和矢量形式OAM的通用器件。本文是主题为“光学轨道角动量”的特刊的一部分。
