1.7-GHz intra-burst repetition rate Yb-fiber amplifier system
Material processing efficiency of ultrafast pulses increases dramatically with repetition rate of the pulses, if the conditions are adjusted correctly to avoid excessive plasma and particulate shielding. However, given that there is a minimum pulse energy requirement, continuous operation at high repetition rates can be detrimental due to too much average power leading to heat accumulation. Burst-mode operation of lasers, wherein the amplifier periodically produces a group of pulses (a burst), which are very closely spaced in time, avoids this problem. However, ultrafast burst-mode lasers are typically limited to several 100 MHz intra-burst repetition rates. While this is sufficient for most materials, metals with high thermal conductivity require higher repetition rates.