Efficient single-mode operation of a cladding-pumped ytterbium-doped helical-core fiber laser Wang, P. ; Cooper, L. J. ; Sahu, J. K. ; Clarkson, W. A. Abstract Publication: Optics Letters Pub Date: January 2006 DOI: 10.1364/OL.31.000226 Bibcode: 2006OptL...31..226W