双缺陷模一维光子晶体的双光子吸收增强研究

采用真空镀膜工艺制备了具有762 nm和800 nm双缺陷模的含两个CdS缺陷层的TiO2/SiO2一维光子晶体,运用抽运探测技术测量了其双光子吸收。对于两个缺陷模,双光子吸收均得到很大的增强,其中缺陷模为800nm时的双光子吸收系数307 cm/GW要大于缺陷模为762 nm时的116 cm/GW,分别为单层CdS薄膜的48倍和18倍。这种双光子吸收的增强是由于光局域化导致一维光子晶体缺陷层内的电场强度增大而形成的。通过传输矩阵法计算了一维光子晶体的内部场强,发现800 nm波长光入射时缺陷层内的电场强度要大于762 nm波长光入射时的电场强度值。

Research on Two-Photon Absorption Enhancement in One-Dimensional Photonic Crystals with Double Defect Modes

One-dimensional photonic crystals with two CdS defect layers which had two defect modes of 762 nm and 800 nm was fabricated by vacuum deposition process.Two-photon absorption coefficient was investigated by pump-probe measurement.The two-photon absorption coefficient was enhanced at two defect modes.307 cm/GW two-photon absorption coefficient at defect mode of 800 nm was greater than 116 cm/GW at defect mode of 762 nm and they were 48 and 18 times as large as that of a single CdS thin film.The enhancement of two-photon absorption coefficients was due to the enhanced electric field intensity ascribed to light localization in the two CdS defect layers.The transfer matrix method was used to calculate the internal electric field intensity in the one-dimensional photonic crystal sample.It was found that the electric field intensity in defect layers at defect mode of 800 nm was larger than that of 762 nm.