Measuring azimuthal and radial modes of photons

Frédéric Bouchard*, Natalia Herrera Valencia, Florian Brandt, Robert Fickler, Marcus Huber, Mehul Malik

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

81 Citations (Scopus)
76 Downloads (Pure)


With the emergence of the field of quantum communications, the appropriate choice of photonic degrees of freedom used for encoding information is of paramount importance. Highly precise techniques for measuring the polarisation, frequency, and arrival time of a photon have been developed. However, the transverse spatial degree of freedom still lacks a measurement scheme that allows the reconstruction of its full transverse structure with a simple implementation and a high level of accuracy. Here we show a method to measure the azimuthal and radial modes of Laguerre-Gaussian beams with a greater than 99 % accuracy, using a single phase screen. We compare our technique with previous commonly used methods and demonstrate the significant improvements it presents for quantum key distribution and state tomography of high-dimensional quantum states of light. Moreover, our technique can be readily extended to any arbitrary family of spatial modes, such as mutually unbiased bases, Hermite-Gauss, and Ince-Gauss. Our scheme will significantly enhance existing quantum and classical communication protocols that use the spatial structure of light, as well as enable fundamental experiments on spatial-mode entanglement to reach their full potential.

Original languageEnglish
Pages (from-to)31925-31941
Number of pages17
JournalOptics Express
Issue number24
Publication statusPublished - 26 Nov 2018

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


Dive into the research topics of 'Measuring azimuthal and radial modes of photons'. Together they form a unique fingerprint.

Cite this