Phase-matched third-harmonic generation in highly germanium-doped fiber

Phase-matched third-harmonic generation is demonstrated in a germanium-doped optical fiber. Green light at 514.4 nm is generated in an LP03 mode when a pump field at similar to 1543.3 nm is launched into the fiber in the fundamental LP01 mode. The phase matching is achieved for a particular combination of the germanium doping concentration and the fiber core diameter. (C) 2012 Optical Society of America