Enhancing the modal purity of orbital angular momentum photons

Isaac Nape, Bereneice Sephton, Yao Wei Huang, Adam Vallés, Cheng-Wei Qiu, Antonio Ambrosio, Federico Capasso, Andrew Forbes

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Orbital angular momentum (OAM) beams with topological charge ℓ are commonly generated and detected by modulating an incoming field with an azimuthal phase profile of the form exp(iℓφ) by a variety of approaches. This results in unwanted radial modes and reduced power in the desired OAM mode. Here, we show how to enhance the modal purity in the creation and detection of classical OAM beams and in the quantum detection of OAM photons. Classically, we combine holographic and metasurface control to produce high purity OAM modes and show how to detect them with high efficiency, extending the demonstration to the quantum realm with spatial light modulators. We demonstrate ultra-high purity OAM modes in orders as high as ℓ = 100 and a doubling of dimensionality in the quantum OAM spectrum from a spontaneous parametric downconversion source. Our work offers a simple route to increase the channel capacity in classical and quantum communication using OAM modes as a basis.
Original languageEnglish (US)
Pages (from-to)070802
JournalAPL Photonics
Issue number7
StatePublished - Jul 13 2020
Externally publishedYes


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