Polarized disk contrast in the near-IR measured with SPHERE/IRDIS in the broadband H (blue markers) and J (red markers) filters, and total scattered-light contrast in the optical measured with HST/STIS (black markers) plotted against the disk fractional IR luminosity. The orange marker represents the scattered-light contrast for HD 129590 measured in the H band with IRDIS. The axis ratio of each elliptical marker corresponds to the ratio of the minor to major axis of the respective disk, representing its inclination. The black dash-dotted line shows a linear fit to the optical total scattered-light contrast measured with HST/STIS for five debris disks (Sect. 6.3.7). The gray-shaded region indicates the 68% confidence interval for the fit. The black solid line shows the fit to the optical total scattered-light contrast obtained by Schneider et al. (2014) for a set of ten debris disks. The blue dashed line denotes a linear fit to the H-band polarized contrast for disks with inclinations higher than 75°, while the blue-shaded region indicates the 68% confidence interval for this fit.