A Tale of Three Dust Populations: Variable $R_{\rm{V}}$ and Extreme
  Polarization Along Sightlines Toward $\zeta$ Ophiuchi
  Dust permeates the interstellar medium, reddening and polarizing background
starlight, but dust properties vary with local environment. In order to
characterize dust in a highly irradiated diffuse cloud, we measure the
reddening and optical polarization towards 27 stars surrounding the
mid-latitude $b$=$+$24$^{\circ}$ O9.2IV star $\zeta$ Ophiuchi, using new
optical spectroscopy and polarimetry. We incrementally deredden and depolarize
with distance, allowing us to distinguish dust components along these
sightlines. The data indicate three distinct dust populations: a foreground
component characteristic of average Milky Way dust ($R_{\rm{V}}$$\approx$3.1,
$d$$\lesssim$180 pc), a highly polarizing mid-distance component in the
vicinity of $\zeta$ Oph ($R_{\rm{V}}$$\approx$2.4, 200 pc$<$$d$$<$300 pc), and
a non-polarizing distant component ($R_{\rm{V}}$$\approx$3.6, 600
pc$<$$d$$<$2000 pc). Prominent 8 $\mu$m infrared striations spanning the field
of view likely have high Polycyclic Aromatic Hydrocarbon content and are
illuminated by $\zeta$ Oph. Foreground-subtracted polarizations roughly align
with these striations, which, we argue, lie immediately behind $\zeta$ Oph and
constitute the highly-polarizing mid-distance dust. This component polarizes
very efficiently ($P_{\rm{V}}$$>$9.1$E(B-V)$), implying a high degree of grain
alignment and suggesting that the bulk of the polarization occurs in a small
fraction of the volume. The large $R_{\rm{V}}$ in the distant component reveals
that dust above the Galactic Plane ($z$$>$250 pc) may contain a greater
fraction of large grains than the Milky Way average.
