Configuration of vortex-antivortex lattices at output mirror of wide-area microchip laser

Square vortex lattices predicted theoretically and experimentally observed in diode-pumped solid state microchip lasers are shown to have a remarkable symmetry. These lattices are formed by counter-rotating vortices. The interaction of vortices with nonlinear gain medium leads to precession of vortices and collective excitations with dynamics identical to acoustical and optical vibrations of atomic lattices.