  Polarization behaviors of optical afterglows from two-component gamma-ray
burst jets are investigated, assuming various configurations for the two
components. In most cases, the observed polarization is dominated by the inner
narrow component for a long period. Interestingly, it is revealed that
different assumptions about the lateral expansion of the jet can lead to
different evolutions of the position angle of polarization. The observed
afterglow light curve and polarization behaviors of GRB 020813 can be well
explained by the two-component jet model. Particularly, the model is able to
explain the constancy of the observed position angle in this event, given that
the line of sight is slightly outside the narrow component.
