Establishing a new photonic material with large optical nonlinearity in the near-infrared regime is significant for ultrafast optical science and devices. In this paper, we developed a facile photochemical approach to fabricate covellite CuS plasmonic nanocrystals (NCs) with high chemical stability and strong oxidation resistance under ambient conditions. The photochemically derived CuS NCs possess strong absorption in the visible-to-near-infrared optical range caused by the localized surface plasmon resonance effect (LSPR). We further demonstrate superior saturable absorption behavior of CuS NCs with a large modulation depth and a high damage threshold. Using CuS as an optical switch, a highly stable mode-locked pulsed laser operating in the telecommunication band with a signal-to-noise ratio over 70 dB and a pulse duration of 1.57 ps has been achieved. Our results suggest that the photochemical method is an effective technique to fabricate plasmonic NCs, which can be developed as an excellent candidate for ultrafast photonic devices in the visible-to-near-infrared region.

中文翻译：

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光化学衍生的等离子体半导体纳米晶体作为超快光子学的光开关

建立一种新的具有近红外光学非线性的光子材料对于超快光学科学和设备具有重要意义。在本文中，我们开发了一种简便的光化学方法来制备在环境条件下具有高化学稳定性和强抗氧化性的Covellite CuS等离子体纳米晶体（NCs）。由于局部表面等离振子共振效应（LSPR），光化学衍生的CuS NCs在可见到近红外光学范围内具有较强的吸收能力。我们进一步证明了具有较大调制深度和较高损伤阈值的CuS NCs的优异的饱和吸收行为。使用CuS作为光开关，可以在电信频段内工作的高度稳定的锁模脉冲激光器，其信噪比超过70 dB，脉冲持续时间为1。已达到57 ps。我们的结果表明，光化学方法是一种制造等离激元NC的有效技术，可以将其开发为可见光至近红外区域中超快光子器件的极佳候选者。