Photonic lantern wavefront reconstruction in a multi-wavefront sensor single-conjugate adaptive optics system

TL;DR

This paper demonstrates the use of photonic lanterns as low-order focal-plane wavefront sensors in multi-wavefront sensor adaptive optics systems, improving aberration correction for high-contrast imaging.

Contribution

It introduces a new method for photonic lantern wavefront reconstruction and integrates it into a multi-WFS AO system, enhancing aberration sensing capabilities.

Findings

Photonic lanterns can effectively sense low-order aberrations in AO systems.

The study compares three wavefront reconstruction algorithms for PLs.

A new experimental method for identifying the PL propagation matrix is proposed.

Abstract

Exoplanet direct imaging using adaptive optics (AO) is often limited by non-common path aberrations (NCPAs) and aberrations that are invisible to traditional pupil-plane wavefront sensors (WFSs). This can be remedied by focal-plane (FP) WFSs that characterize aberrations directly from a final science image. Photonic lanterns (PLs) can act as low-order FPWFSs with the ability to direct some light to downstream science instruments. Using a PL on the SEAL (Santa Cruz Extreme AO Laboratory) high-contrast imaging testbed, we demonstrate (1) linear ranges and (2) closed-loop control. Additionally, we simulate the use of the PL in a multi-wavefront sensor AO system, in which multiple WFSs feed back to the same common-path deformable mirror. Building on previous multi-WFS AO demonstrations on SEAL, we simulate a modulated pyramid WFS to sense aberrations of high spatial order and large amplitude, and the PL to sense low order aberrations including NCPAs. We assess adaptive optics performance in this setting using three different PL wavefront reconstruction algorithms. We also provide a new method to experimentally identify the propagation matrix of a PL, making advanced model-based algorithms practical. This work demonstrates the role of photonic technologies and multi-stage wavefront sensing in the context of extreme AO and high contrast imaging.