Two-dimensional dispersive shock waves in dissipative optical media.

We study generation of two-dimensional dispersive shock waves and oblique dark solitons upon interaction of tilted plane waves with negative refractive index defects embedded into defocusing material with linear gain and two-photon absorption. Different evolution regimes are encountered, including the formation of well-localized disturbances for input tilts below critical one, generation of extended shock waves containing multiple intensity oscillations in the "upstream" region, and gradually vanishing oblique dark solitons in the "downstream" region for input tilts exceeding critical one. The generation of stable dispersive shock waves is possible only below certain critical defect strength.