Arrest of the dynamic lasing mode in microgear lasers

The initially homogeneous distribution of inversion inside the dielectric is spatially patterned by the electric field as soon as the lasing process converts inversion to electromagnetic field energy. This spatial hole burning or density pinning effect is of the same type in the microdisk as well as in the microgear cavity. The broken azimuthal symmetry of the microgear prevents arbitrary azimuthal angles of the lasing mode pattern. The gear like grating arrests the mode. The continuous azimuthal degeneracy of the whispering gallery modes in a microdisk on the other hand enables the mode to shift to regions with higher gain. The simulation of a pumped microdisk shows this effect to begin shortly after the initial relaxation oscillations.