Understanding the formation and evolution of planetary systems is one of the most fundamental challenges in astronomy. To directly image and study young exoplanets and the circumstellar disks they... Show moreUnderstanding the formation and evolution of planetary systems is one of the most fundamental challenges in astronomy. To directly image and study young exoplanets and the circumstellar disks they form from, dedicated high-contrast imaging instruments are built. Several of these instruments have polarimetric modes that are particularly powerful to reach the large contrasts required to directly image these objects as well as to characterize them. This thesis aims to improve the polarimetric sensitivity, accuracy, and capabilities of high-contrast imaging polarimeters for the detection and characterization of exoplanets and circumstellar disks. In addition, this thesis presents the first direct detections of linear polarization from self-luminous planetary mass companions. The focus of this thesis is mostly on ground-based high-contrast imaging, in particular with the instrument SPHERE-IRDIS at the Very Large Telescope. This thesis covers many aspects of high-contrast imaging polarimetry, ranging from theoretical work, calibrations, and the development of new observing techniques to actual scientific polarimetric measurements and astrophysical interpretation. Show less
