  The optical radiation emitted by blazars contains contributions from
synchrotron radiation by relativistic electrons in the jets, as well as thermal
radiation emitted mainly by the Accretion Disk (AD), the Broad Line Region
(BLR) and the host galaxy. The unpolarized radiation components from the AD,
BLR and host galaxy present themselves by decreasing the total polarization in
the optical/ultraviolet(UV) spectrum. A combined model for the Spectral Energy
Distribution (SED) and degree of optical/UV polarization is constructed,
enabling the disentanglement of the synchrotron and AD components. Our model is
applied to the multi-wavelength SED and spectropolarimetry observations of the
Flat Spectrum Radio Quasar 4C+01.02 ($z = 2.1$) in its 2016 July-August flaring
state and July-August 2017 quiescent state, using data from the Fermi Large
Area Telescope, the Southern African Large Telescope and the Las Cumbres
Observatory network of telescopes. By constraining the AD component, the mass
of the super massive black hole is obtained as $3 \times 10^9 \rm M_{\odot}$.
Furthermore, the model retrieves the characteristics of the relativistic
electron distribution in the jet and the degree of ordering of the magnetic
field. Our results highlight the potential of spectropolarimetry observations
for disentangling thermal from non-thermal (jet) emission components and thus
revealing the physics of particle acceleration and high-energy emission in
active galactic nuclei jets.
