125 µJ ultra-short pulses delivered by a PM Yb-doped tapered fiber amplifier

Chirped Pulse Amplification (CPA) is nowadays a widely used method in laser industry to achieve highly energetic ultra-short pulses. To make it as robust and compact as possible, a fibered approach is highly desirable when possible. Nevertheless, the high power density into the core of a fiber may induce detrimental nonlinear effects leading to spectral and temporal quality degradation of the optical pulses. To mitigate this, large Mode Field Diameter (MFD) fibers have been largely studied [1] – [2] . Despite their efficiency, such fibers often lead to spatial beam degradation and non-monolithic set-ups. Fibers with a longitudinally increasing MFD called taper fiber have emerged since 2008 [3] . This geometry results in an all-fiber setup combined with a good beam quality thanks to adiabatic transition of the fundamental mode [3] – [4] and a efficient pump absorption due to non-reciprocal light propagation along the fiber [3] – [4] . We investigate here the ability of this type of fiber to amplify ultra-short pulses beyond 100 µJ in a CPA architecture while keeping pulse compressibility below few picoseconds.