Related Experiment Video
Updated: Feb 8, 2026

Femtosecond Laser Filaments for Use in Sub-Diffraction-Limited Imaging and Remote Sensing
Published on: April 25, 2019
A compact diffractive sorter for high-resolution demultiplexing of orbital angular momentum beams
Gianluca Ruffato1,2, Marcello Girardi1,2, Michele Massari1,2
1Department of Physics and Astronomy 'G. Galilei', University of Padova, via Marzolo 8, 35131, Padova, Italy.
Abstract:
The design and fabrication of a compact diffractive optical element is presented for the sorting of beams carrying orbital angular momentum (OAM) of light. The sorter combines a conformal mapping transformation with an optical fan-out, performing demultiplexing with unprecedented levels of miniaturization and OAM resolution. Moreover, an innovative configuration is proposed which simplifies alignment procedures and further improves the compactness of the optical device. Samples have been fabricated in the form of phase-only diffractive optics with high-resolution electron-beam lithography (EBL) over a glass substrate. A soft-lithography process has been optimized for fast and cheap replica production of the EBL masters. Optical tests with OAM beams confirm the designed performance, showing excellent efficiency and low cross-talk, with high fidelity even with multiplexed input beams. This work paves the way for practical OAM multiplexing and demultiplexing devices for use in classical and quantum communication.
Related Concept Videos
Angular Momentum
Conservation of Angular Momentum
Atomic Orbitals
Principle of Angular Impulse and Momentum
Angular Momentum about an Arbitrary Axis
The velocity of a mass element comprises its translational velocity and the relative velocity instigated by the body's rotation. Substituting the velocity equation into...
Conservation of Angular Momentum: Application

