铜掺杂氧化锌纳米棒的非线性光学响应竞争特性

利用飞秒脉冲激光激发Cu掺杂ZnO纳米棒,研究其特有的非线性光学性质和激发机制。在激发波长为750 nm的荧光光谱中,二次谐波峰非常弱,几乎可以忽略,存在非常强的激子发光峰和Cu掺杂导致缺陷发光峰。激发强度的增大会导致这两个发光峰强度呈非线性增大,激子发光峰位产生明显红移,而缺陷发光峰位没有变化。进一步增大激发强度,缺陷发光峰强度会出现饱和甚至有所下降,而激子发光峰强度持续增大。当激发波长增加到760 nm时,从样品的荧光光谱可以清楚地识别到二次谐波峰和激子发光峰以及缺陷发光峰并存。随着激发波长的进一步增加,二次谐波强度不断增大,而激子发光峰和缺陷发光峰的强度却随之下降。当激发波长为790 nm和800 nm时,未发现激子发光峰和缺陷发光峰,非线性光谱以二次谐波为主导。研究结果表明,通过选择合适的激发波长和激发强度,可以实现发光颜色的转变,使得Cu掺杂ZnO纳米棒在全光显示方面具有潜在的发展前景。

Competition in Nonlinear Optical Properties of Cu-doped ZnO Nanorods

In order to study the unique nonlinear optical properties and excitation mechanism, Cu-doped zinc oxide nanorods were excited by femtosecond pulsed laser. Under the excitation of 750 nm, the second harmonic peak is almost ignore meanwhile only the exciton peak and Cu doping re-lated peak. The increase of the excitation intensity leads to a nonlinear increase of the intensity of the two emission peaks. The position of exciton peak exhibits a red shift meanwhile the position of defect peak does not move. If the excitation intensity further increases, the intensity of the defect re-lated emission will decrease and the intensity of the exciton emission will increase continuously. When the excitation wavelength increases to 760 nm, the fluorescence spectrum of the sample can be clearly recognized the coexistence of the second harmonic peak and the exciton emission as well as the defect related emission. With the increasing of the excitation wavelength, the intensity of the second harmonic increases and the intensity of exciton emission and defect related emission de-crease. At the excitation wavelengths of 790 nm and 800 nm, the exciton emission and defect related emission cannot be found, and the nonlinear spectrum is dominated by second harmonic generation. By selecting the appropriate excitation wavelength and excitation intensity, the transition of theluminescent color display can be realized, which makes Cu-doped ZnO nanorods as the potential of all-optical display.