  The Nancy Grace Roman Space Telescope Coronagraph Instrument will enable the
polarimetric imaging of debris disks and inner dust belts in the optical and
near-infrared wavelengths, in addition to the high-contrast polarimetric
imaging and spectroscopy of exoplanets. The Coronagraph uses two Wollaston
prisms to produce four orthogonally polarized images and is expected to measure
the polarization fraction with measurement errors < 3% per spatial resolution
element. To simulate the polarization observations through the Hybrid Lyot
Coronagraph (HLC) and Shaped Pupil Coronagraph (SPC), we model disk scattering,
the coronagraphic point-response function, detector noise, speckles, jitter,
and instrumental polarization and calculate the Stokes parameters. To
illustrate the potential for discovery and a better understanding of known
systems with both the HLC and SPC modes, we model the debris disks around
Epsilon Eridani and HR 4796A, respectively. For Epsilon Eridani, using
astrosilicates with 0.37+/-0.01 as the peak input polarization fraction in one
resolution element, we recover the peak disk polarization fraction of
0.33+/-0.01. Similarly, for HR 4796A, for a peak input polarization fraction of
0.92+/-0.01, we obtain the peak output polarization fraction as 0.80+/-0.03.
The Coronagraph design meets the required precision, and forward modeling is
needed to accurately estimate the polarization fraction.
