  We show that Anderson localization is possible in waveguide arrays with
periodically-spaced defect waveguides having lower refractive index. Such
localization is mediated by Bragg reflection, and it takes place even if
diagonal or off-diagonal disorder affects only defect waveguides. For
off-diagonal disorder the localization degree of the intensity distributions
monotonically grows with increasing disorder. In contrast, under appropriate
conditions, increasing diagonal disorder may result in weaker localization.
