Abstract: A fiber laser is configured with a double clad fiber with a core doped with ions of Erbium (Er+3) and Ytterbium (Yb+3). At least two spaced apart high and low reflection mirrors flank the core and define a resonant cavity therebetween. The fiber laser further includes a pump laser outputting light in a 1.02-1.06 ?m wavelength range which is coupled into the Yb:Er doped double clad fiber. A fiber amplifier includes a double clad fiber with a core doped with ions of Erbium (Er+3) and Ytterbium (Yb+3), and a pump laser generating radiation at a pump wavelength in a 1.02-1.06 wavelength range, a pump laser outputting light in a 1.02-1.06 ?m wavelength range coupled into the Yb:Er doped double clad fiber. The disclosed fiber laser and fiber amplifier each have a significantly higher lasing threshold in the 1 ?m wavelength range than the threshold of the known schematics operating at a 9xx nm pump wavelength.

Abstract: An optical active fiber is configured with an asymmetrically-shaped core having at least one long axis and a shortest axis which extends transversely to the long axis. The outmost cladding of the active fiber is configured with a marking indicating the orientation of the short axis. The marking allows for bending the fiber so that the shortest axis extends along and lies in the plane of the bend thereby minimizing distortion of a mode which is guided by the asymmetrically-shaped core as light propagates along the bend.