  Waves billiard which are chaotic in the geometrical limit are known to
support non-generic spatially localized modes called scar modes. The
interaction of the scar modes with gain has been recently investigated in
optics in micro-cavity lasers and vertically-cavity surface-emitting lasers.
Exploiting the localization properties of scar modes in their wave analogous
phase space representation, we report experimental results of scar modes
selection by gain in a doped D-shaped optical fiber.
