Ultrafast electron pulses generated using femtosecond lasers offer a direct means for investigating ultrafast processes, but the yield of electron emission remains a significant practical limitation. This study demonstrates a substantial enhancement in yield of electron emission from carbon nanotubes induced by two-color ( + ) pulses with an 80 MHz repetition rate and this enhancement is non-delay-dependent. Compared to the sum of photocurrents induced by each color pulse individually, the combined two-color pulses result in a remarkable enhancement in yield of electron emission by more than 25 times. We attribute this enhanced yield to carrier-assisted optical field emission: carbon nanotubes sustain high carrier concentration state under laser radiation thereby enhancing yield of electron emission. We propose the carrier migration emission model to provide a semi-quantitative description for the carrier-assisted optical field emission. This phenomenon introduces a new method to increase the yield of ultrafast electron pulses from CNTs and paves the way for next-generation ultrafast electron emitters and on chip ultrafast optoelectronic device.

中文翻译：

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双色激光驱动的碳纳米管增强电子发射，具有长载流子寿命


使用飞秒激光器产生的超快电子脉冲为研究超快过程提供了直接手段，但电子发射的产量仍然是一个重大的实际限制。这项研究表明，由重复频率为 80 MHz 的双色 (+) 脉冲诱导的碳纳米管电子发射产量显着增强，并且这种增强不依赖于延迟。与单独由每个颜色脉冲引起的光电流之和相比，组合的两种颜色脉冲导致电子发射产率显着提高25倍以上。我们将这种产量的提高归因于载流子辅助光场发射：碳纳米管在激光辐射下维持高载流子浓度状态，从而提高电子发射的产量。我们提出了载流子迁移发射模型，为载流子辅助光场发射提供半定量描述。这种现象引入了一种提高碳纳米管超快电子脉冲产量的新方法，并为下一代超快电子发射器和片上超快光电器件铺平了道路。