This paper describes an integer multiplier for the light orbital angular momentum (OAM) through circular-sector transformations, whereby the cross-sectional circular shape of the OAM mode is geometrically transformed to circular-sector shape. Our method can be simply understood in complex function theory and the transformation process can be visualized as unwrapping a Riemann surface, including multiple sheets into a single sheet. The conversion accuracy is significantly better than the previous method because our method uses single-step geometric transformation. Our method has strong potential for the spatial mode manipulation of OAM and other useful spatial modes.

• Received 28 February 2019

DOI:https://doi.org/10.1103/PhysRevA.100.063822