Metallic 2D materials can be promising saturable absorbers for ultrashort pulsed laser production in the long wavelength regime. However, preparing and manipulating their 2D structures without layer stacking have been nontrivial. Using a combined experimental and theoretical approach, we demonstrate here that a metallic titanium carbide (Ti 3 C 2 T x ), the most popular MXene 2D material, can have excellent nonlinear saturable absorption properties even in a highly stacked state due to its intrinsically existing surface termination, and thus can produce mode-locked femtosecond pulsed lasers in the 1.9-μm infrared range. Density functional theory calculations reveal that the electronic and optical properties of Ti 3 C 2 T x MXene can be well preserved against significant layer stacking. Indeed, it is experimentally shown that 1.914-μm femtosecond pulsed lasers with a duration of 897 fs are readily generated within a fiber cavity using hundreds-of-layer stacked Ti 3 C 2 T x MXene saturable absorbers, not only being much easier to manufacture than mono- or few-layered ones, but also offering character-conserved tightly-assembled 2D materials for advanced performance. This work strongly suggests that as-obtained highly stacked Ti 3 C 2 T x MXenes can serve as superb material platforms for versatile nanophotonic applications, paving the way toward cost-effective, high-performance photonic devices based on MXenes.

中文翻译：

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高度堆叠的Ti3C2Tx MXenes中的超快锁模，适用于1.9μm红外飞秒脉冲激光

金属2D材料对于长波长范围内的超短脉冲激光生产可能是有希望的可饱和吸收体。但是，在不进行层堆叠的情况下准备和操纵其2D结构并非易事。使用实验和理论相结合的方法，我们在此处证明，最流行的MXene 2D材料金属碳化钛（Ti 3 C 2 T x）由于其固有的存在，即使在高度堆叠的状态下也可以具有出色的非线性饱和吸收特性。表面终止，因此可以产生1.9μm红外范围内的锁模飞秒脉冲激光。密度泛函理论计算表明，Ti 3 C 2 T x MXene的电子和光学性质可以很好地保留，以防显着的层堆叠。实际上，实验证明了1。使用数百层堆叠的Ti 3 C 2 T x MXene饱和吸收体可以在光纤腔内轻松产生914μm飞秒脉冲激光，持续时间为897 fs，它不仅比单层或几层更容易制造，而且制造起来也很容易，而且还提供了节省字符的紧密组装的2D材料，以实现更高的性能。这项工作有力地表明，所获得的高度堆叠的Ti 3 C 2 T x MXenes可以作为通用纳米光子应用的绝佳材料平台，从而为基于MXenes的具有成本效益的高性能光子器件铺平了道路。而且还提供了节省字符的紧密组装的2D材料，以提供更高的性能。这项工作有力地表明，所获得的高度堆叠的Ti 3 C 2 T x MXenes可以作为通用纳米光子应用的绝佳材料平台，从而为基于MXenes的具有成本效益的高性能光子器件铺平了道路。而且还提供了节省字符的紧密组装的2D材料，以提供更高的性能。这项工作有力地表明，所获得的高度堆叠的Ti 3 C 2 T x MXenes可以作为通用纳米光子应用的绝佳材料平台，从而为基于MXenes的具有成本效益的高性能光子器件铺平了道路。