# Observing Exoplanets with High-Dispersion Coronagraphy. II. Demonstration of an Active Single-Mode Fiber Injection Unit

## TL;DR

This paper demonstrates a novel high-dispersion coronagraphy system that efficiently injects exoplanet light into a single-mode fiber, enabling high-resolution spectroscopy and speckle suppression for exoplanet characterization.

## Contribution

It introduces an innovative fiber injection unit linking high-contrast imaging to high-resolution spectrographs, with key milestones including high efficiency, precise pointing, and speckle nulling.

## Key findings

- Achieved near-theoretical injection efficiency.
- Demonstrated accurate pointing and tracking.
- Outperformed conventional speckle nulling by over two orders of magnitude.

## Abstract

High-dispersion coronagraphy (HDC) optimally combines high contrast imaging techniques such as adaptive optics/wavefront control plus coronagraphy to high spectral resolution spectroscopy. HDC is a critical pathway towards fully characterizing exoplanet atmospheres across a broad range of masses from giant gaseous planets down to Earth-like planets. In addition to determining the molecular composition of exoplanet atmospheres, HDC also enables Doppler mapping of atmosphere inhomogeneities (temperature, clouds, wind), as well as precise measurements of exoplanet rotational velocities. Here, we demonstrate an innovative concept for injecting the directly-imaged planet light into a single-mode fiber, linking a high-contrast adaptively-corrected coronagraph to a high-resolution spectrograph (diffraction-limited or not). Our laboratory demonstration includes three key milestones: close-to-theoretical injection efficiency, accurate pointing and tracking, on-fiber coherent modulation and speckle nulling of spurious starlight signal coupling into the fiber. Using the extreme modal selectivity of single-mode fibers, we also demonstrated speckle suppression gains that outperform conventional image-based speckle nulling by at least two orders of magnitude.