Eigenmodes of aberrated systems: the tilted lens

TL;DR

This paper investigates the eigenmodes of aberrated optical systems, specifically a tilted lens, using a quantum-inspired approach to identify modes that propagate unchanged, with potential applications in correcting distortions.

Contribution

It introduces an analytical method to find eigenmodes of aberrated systems like the tilted lens, demonstrating robustness and potential for broader application in complex optical channels.

Findings

Eigenmodes of the tilted lens are derived analytically.

Eigenmodes show robustness in practical experiments.

Method can be extended to other astigmatic systems.

Abstract

When light is passed through aberrated optical systems, the resulting degradation in amplitude and phase has deleterious effects, for example, on resolution in imaging, spot sizes in focussing, and the beam quality factor of the output beam. Traditionally this is either pre- or post-corrected by adaptive optics or phase conjugation. Here we consider the medium as a complex channel and search for the eigenmodes of the channel, the modes that propagate through this system without alteration. We employ a quantum-inspired approach and apply it to the tilted lens as our example channel, a highly astigmatic system that is routined used as a desired distortion inducer to measure orbital angular momentum. We find the eigenmodes analytically, show their robustness in a practical experiment, and outline how this approach may be extended to arbitrary astigmatic systems.