Digital Optical Technologies

Nonlinear digital holography for light-speed correction of structured light

Sachleen Singh, Andrew Forbes

Published Aug 5, 2025• 0 citations

Abstract

Structured light has enabled major advances in areas like communication and imaging, but real-world optical aberrations severely distorts the amplitude and phase structures of light during propagation. Traditional correction methods rely on measuring and reversing these distortions using adaptive optics or transmission matrix approaches, which are limited by slow electronic feedback. Here, we present a fast, measurement-free method to correct distorted structured light, especially orbital angular momentum (OAM) modes, using a nonlinear optical process. By co-propagating a probe and signal beam through the same aberrated channel and overlapping them in a nonlinear crystal, we exploit difference frequency generation (DFG) to perform phase conjugation. This naturally reverses distortions at the speed of light, without any prior knowledge of the channel. We demonstrate the recovery of complex modes across a wide range of aberrations and verify the method’s robustness using a 15-dimensional OAM alphabet, achieving strong signal restoration. Our demonstration of light correcting light without the need for measurement opens a new approach to measurement-free error correction for classical and quantum structured light, with direct applications in imaging, sensing, and communication.

DOI: 10.1117/12.3067836

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