Detecting and characterizing close-in exoplanets with Vortex Fiber Nulling

TL;DR

Vortex Fiber Nulling (VFN) is a promising interferometric technique that suppresses starlight to detect and characterize close-in exoplanets, with recent lab demonstrations achieving high null depths and ongoing upgrades for infrared observations.

Contribution

This paper reports the latest lab results of VFN, including polychromatic nulls, and updates on the development of an upgraded testbed and infrared nulling capabilities for future on-sky use.

Findings

Achieved polychromatic nulls of 5×10⁻⁴ in 10% bandwidth at 790 nm

Designed and built an upgraded VFN testbed for improved performance

Presented preliminary K-band nulling results for future on-sky observations

Abstract

Vortex Fiber Nulling (VFN) is an interferometric method for suppressing starlight to detect and spectroscopically characterize exoplanets. It relies on a vortex phase mask and single-mode fiber to reject starlight while simultaneously coupling up to 20% of the planet light at separations of $\lesssim1\lambda/D$, thereby enabling spectroscopic characterization of a large population of RV and transit-detected planets, among others, that are inaccessible to conventional coronagraphs. VFN has been demonstrated in the lab at visible wavelengths and here we present the latest results of these experiments. This includes polychromatic nulls of $5\times10^{-4}$ in 10% bandwidth light centered around 790 nm. An upgraded testbed has been designed and is being built in the lab now; we also present a status update on that work here. Finally, we present preliminary K-band (2 $\mu$m) fiber nulling results with the infrared mask that will be used on-sky as part of a VFN mode for the Keck Planet Imager and Characterizer Instrument in 2021.