An edge dislocation caused a strain dipole field with compressive strain on one and tensile strain on the other side of the dislocation. This strain dipole of single edge dislocations was observed via the tiny spectral shift which it caused to the narrow lines of the donor bound exciton at low temperatures. It was demonstrated that the microscopic orientation of the Burgers vector given by the hexagonal lattice caused the orientation of these strain dipoles along six discrete directions at macroscopic scale. A 2-dimensional convolution method, using a complex convolution core, was also introduced for the  accurate determination of the strain dipole orientation.

Strain of Single Edge Dislocations in Bulk GaN. N.Gmeinwieser, U.T.Schwarz: Physica Status Solidi B, 2007, 244[6], 1857-61