用一维光子带隙结构增强硫化镉双光子吸收研究

用真空镀膜方法制备了含有单个CdS缺陷层的具有不同周期和结构参量的TiO2／SiO2一维光子晶体。用抽运一探测技术研究了CdS缺陷层的双光子吸收（TPA）现象。实验结果表明：一维光子晶体中CdS缺陷层的双光子吸收显著增强。不同周期和结构参量的一维光子晶体中CdS缺陷层的双光子吸收系数不同。双光子吸收的增强来源于由光局域化导致的缺陷层的电场强度的增加。缺陷层电场强度与一维光子晶体的结构有关，如周期，光子带隙的位置与宽度及缺陷模式等因素都会影响缺陷层电场强度。采用四分之一波长的高低折射率介质层和与入射波长匹配的缺陷模可以得到最大的缺陷层电场强度。

Research on Two-Photon Absorption Enhancement of CdS in One-Dimensional Photonic Band Gap Structures

One-dimensional photonic crystals (1D PC) with single CdS defect layer in TiO_2/SiO_2 dielectric thin films stack with different periods and structural parameters were fabricated by vacuum deposition. Two-photon absorption (TPA) of the CdS defect layer in the photonic crystals was investigated by pump-probe measurement. Experimental results show a significant enhancement of TPA coefficient in the CdS defect layer in one-dimensional photonic crystal. Different magnitude of enhanced two-photon absorption coefficient of CdS defect layer in one-dimensional photonic crystal with different photonic band gap has been observed. The enhanced two-photon absorption effect results from the electric field enhancement due to the light localization in the CdS defect layer. The electric field enhancement in defect laser was determined by the structural parameters of one-dimensional photonic crystal such as period, the position and width of bandgap and defect mode. The highest electric field intensity at defect layer is obtained with the alternated quarter-wavelength dielectric thin films of high and low refractive indexes and a defect mode matched with incident light wavelength.