High power and high energy ultrashort pulse generation with a frequency shifted feedback fiber laser.

The highest average power that has been achieved with a frequency-shifted feedback modelocked fiber laser is reported. Subpicosecond pulses with 40 kW peak power are obtained by this technique for the first time by using external pulse compression. The pulsing is self starting and environmentally stable. The measured pulse energy in modelocked operation is 120 nJ. The pulses could be compressed to 855 fs. The pulse energy was increased to 1muJ with controlled Q-switched modelocking.