【摘要】 制备了乙醇 二氧化硅三维胶质光子晶体 ,其晶格常数随着晶体高度的变化而变化 .用皮秒脉冲激光在不同高度激发光子晶体中乙醇产生Raman信号 ,得到了两个结果 :1 )即使Raman信号的中心频率与光子晶体的带隙中心频率一致 ,在其禁带方向上测得的强度也没有被抑制到与带隙深度同样的量级 ;2 )尽管单纯的具有Raman信号频率的入射光的透过率随着高度的变化而剧烈变化 ,但在光子晶体中产生的Raman信号强度却几乎不随高度的变化而变化 ,即光子晶体的赝带隙几乎没有影响在禁带方向上测得的Raman信号强度 .基于“光子晶体带隙对入射光和内部光源传播影响不同”的物理机理 ,比较合理地解释了这两个实验结果 ,即探测到的较大Raman信号强度来源于光子晶体内部缺陷对内部Raman信号的散射和光子晶体外表面直接产生的Raman信号更多还原

【Abstract】 A silica colloidal photonic crystal in ethanol solution, whose lattice constant varies with the height of the crystal, was prepared. The Raman intensities of the ethanol solution induced by a picosecond intense laser were measured at different heights, and two phenomena were found: (1) although the frequency of Raman signals generated within the photonic crystal is equal to that of the photonic pseudogap of the photonic crystal, the Raman intensity attenuation measured is not reduced to the extent of that in the conventional transmission experiment; (2) although the transmission of an incident beam with the wavelength of the Raman signal is strongly dependent on the height of crystal, the intensity of the Raman scattering generated within the silica ethanol colloidal photonic crystal does not change with the height, i.e. it is insensitive to the pseudogap. These anti intuitive phenomena may be directly interpreted using the fact that the propagation mechanism of the monodirectional incidental laser is intrinsically different from that of the Raman signals from inner light sources inside a photonic crystal, and the Raman signals scattered by defects deep inside the crystal and generated in the surface layer contribute largely to the measured intensities.更多还原