Day 2 of the OAM Incubator

Optica Blog

Day 2 of the OAM Incubator

Kaitlyn Morgan, Clemson University

Day one of the orbital angular momentum (OAM) Incubator concluded with a session on Communications. This session covered several types of optical communications and how we can begin to improve these systems. Alan Willner, University of Southern California, (pictured here) discussed potential applications for unmanned vehicles, underwater communications, and even quantum communications, highlighting multiplexing techniques the exploit the orthogonality of OAM. Next Akbar Sayeed, National Science Foundation, discussed fundamental limitations in the power, bandwidth, and spatial dimensions of these systems. His talk highlighted our potential ability to exploit more of the spatial dimension, comparing capabilities with MIMO, a multiple input – multiple output communications system most commonly used with radio frequencies. The final speaker, Abbie Watnik, US Naval Research Lab, demonstrated machine learning capabilities for the detection of OAM optical signals through turbulence, comparing Bessel-Gaussian and Laguerre-Gaussian beams. Her neural network had better performance with Bessel-Gaussian beams and has the potential ability to sense and characterize turbulence. This session continued on with a lively discussion and continued into dinner.

As day two began, the speakers started to connect many of yesterday’s different talks together like the pieces of a jigsaw puzzle. The final topic, Sensing and Imaging, was similar to the Communications session, but was focused on exploiting system imperfections as a sensing mechanism.

From the Rochester Institute of Technology, Grover Swartzlander’s talk taught us about mathematically ideal optical vortices and how they differ from what we can create experimentally. “To quote Obi Wan,” he later said, “These are not the vortices you are looking for.” He also presented his work with broadband vortex generation and optical coronagraphs, commonly used in astronomy to see around bright stars. Mark Lieber, Ball Aerospace & Technologies, discussed the effect of scattering from particles and surfaces on OAM for LIDAR (light-radar), and used OAM to measure the rotational frequency of a spinning target. Host Brandon Cochenour, from the Naval Air Warfare Center discussed using an optical coronagraph to separate scattered and ballistic light underwater for use as a transmissometer and to detect faint return signals. Aristide Dogariu, University of Central Florida, delved into the use of structured light for object tracking, focusing on stochastic sensing, where an object is illuminated with a sequence of patterns and can be recovered with a sequence of power measurements. The final speaker, Andrei Afanasev, George Washington University, demonstrated how OAM can be transferred from light to bound electrons, with potential applications in spectroscopy and with semiconductor materials.

As the OAM incubator came to a close, there was one final session to wrap-up and discuss what should come next. The group was in agreement that next steps were needed to continue the discussion and further explore applications. The hosts will be working with OSA to determine the best path forward – another Incubator or maybe even some special sessions at other OSA meetings.

I think everyone appreciated the opportunity to discuss their work and bounce around ideas with this extremely knowledgeable group of people. The use of OAM in optical systems is relatively new, and there is still much to explore theoretically, especially in modal space, and to help improve the use of OAM in applications such as the propagation of laser beams through harsh environments. Be on the lookout for more on OAM in The Optical Society’s OPN magazine and maybe even a special issue related to this topic in one of OSA’s peer-reviewed journals!

Aristide Dogariu, University of Central Florida, finishes his talk on Structured Wavefronts for Optical Sensing with a little levity.

There were even a few posters sparking interest and discussion at this Incubator.