Broadband Wavefront Control with a Single Mode Fiber: 1E-8 Raw Contrast Over 20% Bandwidth

Abstract

A pathway to maximizing the scientific yield of future exoplanet imaging instruments is to develop technologies that give access to high levels of contrast over large bandwidths. Combining the use of deformable mirrors (DMs) for wavefront control and a single mode fiber (SMF) in the image plane has been proven to enhance the contrast achievable for broadband characterization of exoplanet atmospheres. Indeed, the modal selectivity of the SMF aids with the rejection of speckles in the vicinity of the companion. Furthermore, the stroke requirements on the DMs needed to achieve high levels of raw contrast are relaxed given the reduced number of spatial frequencies seen by the SMF. Here we report on the status of our SMF wavefront control experiments at the High-Contrast Spectroscopy Testbed (HCST) in the Exoplanet Technology Laboratory at Caltech: we have reached 1×10−8 raw contrast over 20% bandwidth with an SMF. © 2023 SPIE.