Steinke, M Co-seeded Er3+:Yb3+ single frequency fiber amplifier with 60 W output power and over 90% TEM(00) content. [electronic resource] - Optics express Jul 2014 - 16722-30 p. digital Publication Type: Journal Article; Research Support, Non-U.S. Gov't ISSN: 1094-4087 Standard No.: 10.1364/OE.22.016722 doi