  We study the benefits of polarimetry observations of microlensing events to
detect and characterize circumstellar disks around the microlensed stars
located at the Galactic bulge. These disks which are unresolvable from their
host stars make a net polarization effect due to their projected elliptical
shapes. Gravitational microlensing can magnify these signals and make them be
resolved. The main aim of this work is to determine what extra information
about these disks can be extracted from polarimetry observations of
microlensing events in addition to those given by photometry ones. Hot disks
which are closer to their host stars are more likely to be detected by
microlensing, owing to more contributions in the total flux. By considering
this kind of disks, we show that although the polarimetric efficiency for
detecting disks is similar to the photometric observation, but polarimetry
observations can help to constraint the disk geometrical parameters e.g. the
disk inner radius and the lens trajectory with respect to the disk semimajor
axis. On the other hand, the time scale of polarimetric curves of these
microlensing events generally increases while their photometric time scale does
not change. By performing a Monte Carlo simulation, we show that almost 4
optically-thin disks around the Galactic bulge sources are detected (or even
characterized) through photometry (or polarimetry) observations of
high-magnification microlensing events during 10 years monitoring of 150
million objects.
