  The structure of magnetic fields within protostellar disks may be studied via
polarimetry provided that grains are aligned in respect to magnetic field
within the disks. We explore alignment of dust grains by radiative torque in T
Tauri disks and provide predictions for polarized emission for disks viewed at
different wavelengths and viewing angles. We show that the alignment is
especially efficient in outer part of the disks. In the presence of magnetic
field, these aligned grains produce polarized emission in infrared wavelengths.
We consider a simple model of an accretion disk and provide predictions for
polarization that should be available to both instruments that do not resolve
the disks and future instruments that will resolve the disks. As the surface
magnetic field and the bulk magnetic field play different roles for the disk
dynamics, we consider separately the contributions that arises from the surface
areas of the disk and its interior. We find that the polarized emission drops
for wavelengths shorter than $\sim 10 \mu m$. Between $\sim 10 \mu m$ and $\sim
100 \mu m$, the polarized emission is dominated by the emission from the
surface layer of the disks and the degree of polarization can be as large as
$\sim 10%$ for unresolved disks. The degree of polarization is around 2-3 %
level at wavelengths larger than $\sim100\mu m$.
