High peak power stretcher free femtosecond fiber amplifier using passive spatio temporal coherent combining.
We report on the passive coherent combining of up to 8 temporally and spatially separated ultrashort pulses amplified in a stretcher free ytterbium doped fiber system. An initial femtosecond pulse is split into 4 temporal replicas using divided pulse amplification, and subsequently divided in two counter propagating beams in a Sagnac interferometer containing a fiber amplifier. The spatio temporal distribution of the peak power inside the amplifier allows the generation of record 3.1 uJ and 50 fs pulses at 1 MHz of repetition rate with 52 MW of peak power from a stretcher free fiber amplifier and without additional nonlinear post compression stages.
Optics express