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采用超短脉冲近红外光(1.06μm)激发,首先在多孔硅表面观察到了较强的可见区荧光产生.荧光强度与激发光强度的三次方关系表明,有效的荧光产生起源于三阶非线性光学效应的增强.对多孔度低的样品观察不到这种荧光发射.通过与多孔硅的紫外光(355 nm)激发谱的比较,我们把这种有效的多光子激发过程归结为来源于多孔硅的量子约束效应.
First, the fluorescence of visible region was observed on the surface of porous silicon by using ultrashort pulse NIR (1.06μm) excitation.The cubic relationship between fluorescence intensity and excitation light intensity showed that the effective fluorescence originated from the third-order nonlinearity The optical effect was enhanced.It was not observed for samples with low porosity.Compared with the excitation spectrum of porous silicon (355 nm), we attribute this effective multiphoton excitation process to porous Quantum confinement effect of silicon.