Axisymmetric toroidal wave fronts are pertinent to the near forward and backward scattering by objects that have rotational symmetry. For spheres, the wave field produced by such a wave front is known as glory scattering. As the wave front propagates, ome porton of it becomes focused on an axis, forming a structurally unstable line caustic. A specific lass of harmonic perturbations of the wave ...

The development of hollow core photonic crystal fibers with low losses over a broad spectral region in the near IR enabled the demonstration of a novel laser type Hollow-core Optical Fiber Gas Laser (HOFGLAS). The laser combines attractive features of fiber lasers such as compactness and long interaction length of pump and laser radiation with those of gas lasers such as the potential for high ...