A study of novel optical responses and enhancement of optical nonlinearities in carbon nanotubes by ultrafast laser spectroscopy

在金属碳纳米管中，我们成功地观测到了寿命为40ps的激子光致发光。由飞秒发光光谱测得空穴掺杂半导体纳米管中三电子的形成时间和弛豫时间分别为80fs和380fs。在包裹金属富勒烯的半导体碳纳米管中，观察到了从金属富勒烯到纳米管的载流子掺杂效应，并研究了三阶非线性光学响应。我们还研究了在飞秒时间范围内激子在纳米管之间的能量转移。

In metallic carbon nanotubes, we have succeeded to observe photoluminescence due to excitons with the lifetime of 40 fs. From femtosecond luminescence spectroscopy, the formation and relaxation times of trions in hole-doped semiconducting nanotubes are found to be 80 fs and 380 fs, respectively. In semiconducting carbon naotubes encapsulating metallofullerenes, a carrier doping effect from metallofullerenes to nanotubes is observed, and third-order nonlinear optical responses are investigated. We have also investigated exciton energy transfer between nanotubes in the femtosecond time region.