Choice of optical transformation for photonic circuit wavefront sensors

TL;DR

This paper investigates optimal optical configurations for photonic circuit wavefront sensors to maximize sensitivity to phase aberrations, enhancing exoplanet imaging capabilities.

Contribution

It compares direct coupling and mode sorter coupling methods, providing a framework to design photonic circuits with maximum phase aberration sensitivity.

Findings

Constructed a unitary matrix for maximum sensitivity in photonic circuits.

Compared two coupling approaches: direct and mode sorter.

Provided guidelines for configuring photonic circuits for wavefront sensing.

Abstract

Coronagraph designs which use photonic integrated circuits have the highest theoretical throughput for off-axis signals, and therefore the highest potential exoplanet yield for future high-contrast direct imaging campaigns. Using the rejected starlight, the photonic integrated circuit may also provide simultaneous wavefront sensing, allowing for the correction of non-common-path aberrations. This work considers how a photonic circuit should be configured to maximize its sensitivity to phase aberrations. Two cases are considered: in the first, the photonic circuit is coupled directly to an electric field in a piecewise manner, while in the second, the circuit is coupled to the field via an optical mode sorter. In either case, this work constructs a unitary matrix which can be applied by a photonic circuit to produce maximum sensitivity.