Eigenmodes of aberrated systems: the tilted lens

Abstract

When light propagates through aberrated optical systems, the resulting degradation in amplitude and phase has deleterious effects, for example, on resolution in imaging, spot sizes in focusing, 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 determine the corresponding eigenmodes which are impervious of the channel perturbation. We employ a quantum-inspired approach and apply it to the tilted lens as our example channel, a highly astigmatic system that is routinely used as a measure of 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.

Structurally Stable Astigmatic Vortex Beams with Super-High Orbital Angular Momentum (ABCD Matrix Approach)

“…One cannot help but remark that astigmatic processes accompany almost all optical measurements, unexpectedly manifesting themselves in light reflections and refractions on surfaces [25] or inaccurate alignment of spherical lenses [26] or cylindrical lense [26], which at once leads to distortion of the OAM laser beam. The variety of measuring techniques of these distortions is striking, ranging from standard approaches [27] and tomographic methods with mapping the distortion process onto the Poincare sphere [28] up to involving the machine learning [29].…”