Coherently combined fiber laser system delivering 120 μJ femtosecond pulses

Abstract

We report on the coherent combination of two chirped pulsed fiber lasers. The beams coming from two 100 μm core diameter ytterbium-doped rod-type fibers were coupled in a Mach-Zehnder-type interferometer by means of a polarization beam splitter. Active stabilization of the interferometer was achieved by using a piezo-mounted mirror driven by a Hänsch-Couillaud polarization detection system. Pulses with 120 μJ energy and a compressed duration of 800 fs were obtained. This, compared with the 66 μJ coming from each single amplifier, results in a combining efficiency as high as 91%.