Generation of frequency-doubled 55 fs pulses from an Erbium fiber laser system

We report on the frequency doubling of an Erbium-doped master-oscillator power-amplifier system. The fundamental 72 fs pulses at a wavelength of 1.56 µm are frequency doubled to 780 nm and compressed in a Gires-Tournois-interferometer mirror pair to a duration of 55 fs with an average power of 172 mW with an efficiency of 48 %. To our knowledge these are the shortest pulses ever reported from a frequency-doubled fiber-laser system.