Bartulevicius Tadas, Lipnickas Mykolas, Petrauskiene Virginija, Madeikis Karolis, Michailovas Andrejus
Opt Express. 2022 Sep 26;30(20):36849-36862. doi: 10.1364/OE.472907.
Laser sources which produce GHz bursts of ultrashort pulses attract a lot of attention by demonstrating superior performance in material processing. Flexibility of the laser source in a selection of parameters for custom application is highly preferable. In this work, we demonstrate a very versatile method for burst formation using the active fiber loop (AFL). It allows forming GHz bursts containing from 2 up to approximately 2200 pulses in a burst (1000 ns burst width) with identical pulse separation and any predefined intra-burst pulse repetition rate (PRR). The burst pre-shaping by the amplification conditions in the AFL and by the modulation of transmission of the acousto-optic modulator was demonstrated. Industrial-grade ultrafast laser system was able to operate in the single-pulse and GHz-burst regimes. The laser system delivered high-quality 368 fs duration (FWHM) pulses of 15.3 µJ pulse energy and 30.6 W average output power at 2 MHz PRR in the single-pulse regime. In the GHz-burst operation regime, bursts of 2.2 GHz intra-burst repetition rate were formed and amplified to more than 30 W average output power with a burst energy up to 135 µJ at a burst repetition rate of 200 kHz. The sub-picosecond duration of pulses was obtained in the GHz-burst regime at different burst widths.
能够产生千兆赫兹超短脉冲串的激光源，因其在材料加工中展现出卓越性能而备受关注。激光源在为定制应用选择参数时的灵活性是非常可取的。在这项工作中，我们展示了一种使用有源光纤环（AFL）形成脉冲串的非常通用的方法。它能够形成脉冲串宽度为1000纳秒、包含2至约2200个脉冲的千兆赫兹脉冲串，脉冲间隔相同且具有任何预定义的脉冲串内脉冲重复率（PRR）。通过有源光纤环中的放大条件和声光调制器的传输调制，展示了脉冲串预整形。工业级超快激光系统能够在单脉冲和千兆赫兹脉冲串模式下运行。在单脉冲模式下，该激光系统在2兆赫兹的脉冲重复率下，输出脉宽为368飞秒（半高宽）、脉冲能量为15.3微焦、平均输出功率为30.6瓦的高质量脉冲。在千兆赫兹脉冲串运行模式下，形成了脉冲串内重复率为2.2千兆赫兹的脉冲串，并将其放大至平均输出功率超过30瓦，在200千赫兹的脉冲串重复率下，脉冲串能量高达135微焦。在不同脉冲串宽度的千兆赫兹脉冲串模式下，获得了亚皮秒级的脉冲持续时间。
