In this Letter, we describe a novel, to the best of our knowledge, device based on micro-structured graphene, referred to as zebra-patterned graphene saturable absorber (ZeGSA), which can be used as a saturable absorber with adjustable loss to initiate femtosecond pulse generation. Femtosecond laser micro-machining was employed to ablate monolayer graphene on an infrasil substrate in the form of stripes with a different duty cycle, resulting in the formation of regions with variable insertion loss in the 0.21%–3.12% range. The mode-locking performance of the device was successfully tested using a ${{\rm Cr}^{4 {+} }}{:}\,{\rm forsterite}$ laser, operating near 1250 nm. In comparison with mode locking using non-ablated graphene, the ZeGSA device with regions of decreasing graphene, enabled improved power performance where the mode-locked output power increased from 68 mW to 114 mW, and the corresponding pulse duration decreased from 62 to 48 fs at the same incident pump power of 6.3 W. These experiments indicate that ZeGSA shows great potential as a laser mode locker with adjustable loss and that it should find applications in the development of femtosecond lasers over a broad spectral range.

中文翻译：

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激光微加工斑马纹石墨烯作为可调节损耗的模式锁

在这封信中，我们就我们所知，描述了一种基于微结构石墨烯的新型装置，称为斑马纹石墨烯可饱和吸收剂（ZeGSA），该器件可用作损耗可调的可饱和吸收剂以引发飞秒脉冲产生。飞秒激光微加工被用来烧蚀衬底上呈占空比不同的条纹形式的单层石墨烯，从而形成具有0.21％–3.12％可变插入损耗的区域。已使用$ {{\ rm Cr} ^ {4 {+}}} {：} \，{\ rm forsterite} $成功测试了设备的锁模性能。激光，工作在1250 nm附近。与使用非烧蚀石墨烯的锁模相比，具有减少石墨烯区域的ZeGSA器件可实现更高的功率性能，其中锁模输出功率从68 mW增加到114 mW，相应的脉冲持续时间从62 fs减少到48 fs在相同的6.3 W入射泵浦功率下，这些实验表明ZeGSA作为具有可调节损耗的激光模式锁定器显示出巨大的潜力，它应该在飞秒激光器的广泛光谱开发中找到应用。