3.5-GHz intra-burst repetition rate ultrafast Yb-doped fiber laser

•To our knowledge, first burst-mode fiber laser system with multi-GHz rep-rates.•Optimized for low ASE operation at low burst repetition rates.•Highly-cascaded fiber-integrated architecture designed to achieve high energy bursts.•3.5 GHz intra-burst rep. rate, min 15 ns long bursts at 1 μm wavelength.•Can find numerous applications in ultrafast laser-material and tissue processing

We report on an all-fiber Yb laser amplifier system with an intra-burst repetition rate of 3.5 GHz. The system is able to produce minimum of 15-ns long bursts containing approximately 50 pulses with a total energy of 215μJ at a burst repetition rate of 1 kHz. The individual pulses are compressed down to the subpicosecond level. The seed signal from a 108 MHz fiber oscillator is converted to approximately 3.5 GHz by a multiplier consisting of six cascaded 50/50 couplers, and then amplified in ten stages. The highly cascaded amplification suppresses amplified spontaneous emission at low repetition rates. Nonlinear interactions between overlapping pulses within a burst is also discussed.