SLM phase mask optimization for fiber OAM mode excitation

Antonio Astorino (Invited author), Andrew Rafael Bañas (Invited author), Karsten Rottwitt (Invited author), Jesper Glückstad (Invited author)

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

256 Downloads (Pure)


Fiber orbital angular momentum (OAM) modes can be employed in mode-division multiplexing to increase the channel capacity in optical communication systems. Over the years, several experiments to excite high-purity OAM modes by using one phase-only spatial light modulator (SLM) have been conducted. Since phase-only SLMs are intrinsically imperfect for this purpose due to the impossibility to simultaneously modulate both amplitude and phase in the light source, optimal phase masks need to be generated by iterative algorithms. However, if the state of every pixel in the mask is an unknown of the problem, the computational cost is extremely high. The system circular symmetry can be exploited to overcome this issue. Here, for the first time, this approach is implemented and a simple machine learning algorithm is developed to calculate optimal phase masks with a low number of unknowns and iterations. Simulated and experimental results show that the developed technique is capable of exciting high-purity OAM modes.
Original languageEnglish
Title of host publicationProceedings of SPIE
EditorsJesper Glückstad, David L. Andrews, Enrique J. Galvez
Number of pages8
PublisherSPIE - International Society for Optical Engineering
Publication date2019
Article number109350F
Publication statusPublished - 2019
EventComplex Light and Optical Forces XIII - The Moscone Center, San Francisco, United States
Duration: 5 Feb 20197 Feb 2019
Conference number: SPIE Conference 10935


ConferenceComplex Light and Optical Forces XIII
NumberSPIE Conference 10935
LocationThe Moscone Center
CountryUnited States
CitySan Francisco
SeriesS P I E - International Society for Optical Engineering. Proceedings


  • Orbital angular momentum of light
  • Fiber mode excitation
  • Gradient descent
  • Spatial light modulator
  • Machine learning

Cite this

Astorino, A., Bañas, A. R., Rottwitt, K., & Glückstad, J. (2019). SLM phase mask optimization for fiber OAM mode excitation. In J. Glückstad, D. L. Andrews, & E. J. Galvez (Eds.), Proceedings of SPIE (Vol. 10935). [109350F] SPIE - International Society for Optical Engineering. S P I E - International Society for Optical Engineering. Proceedings, Vol.. 10935