Fabrication of Artificial Anisotoropic Media and Its Applications to Optical Devices and Memories

人工光学各向异性介质，包括周期介质多层膜、多孔介质膜、柱状介质膜和金属岛膜，已被用于光学器件和光学存储。在周期介质多层膜中，TE极化的有效折射率高于TM极化。另一方面，在多孔介质膜和柱状介质膜中，TE极化的有效折射率较低。在这项工作中，提出并研究了用于玻璃集成光学的新型波导型偏振器和偏振分束器。我们已经成功地证明了使用纳米结构的人工光学各向异性介质将用于集成光学，因为可以诱导出理想的双折射。此外，我们还研究了由高密度的金属纳米团簇组成的金属岛膜，用于CD-R型光学数据存储介质。金属岛膜在可见光和近红外区表现出反常的共振型吸收。由于金属岛膜在共振波长具有较大的吸收和较高的反射率，可以代替CD-R的吸收和反射层。在这项工作中，我们成功地展示了利用金属岛膜制作CD-R型光学数据存储介质的初步实验。实验证实，聚焦激光束照射形成了清晰的痕迹。我们还讨论了所提出的金属岛膜光学数据存储介质在多波长和多偏振光盘上的应用。

Artificial optical anisotropic media, including periodic dielectric multilayers, porous dielectric films, columnar dielectric films, and metal island films have been investigated for optical devices and optical memories.In the periodic dielectric multilayers, the effective refractive index for TE polarization is higher than that for TM polarization. On the other hand, in porous dielectric films and columnar dielectric films, the effective refractive index for TE polarization is lower. In this work, novel waveguide polarizers and polarization splitters using those have been proposed and investigated for glass integrated optics. We have successfully shown that the artificial optical anisotoropic media using nano-structures would be useful for integrated optics as desirable birefringence can be induced.In addition, we have investigated the metal island films, composed of metal nanoclusters of high density, for CD-R type optical data storage media. The metal island films exhibit anomalous resonance-type absorption in the visible and near-infrared regions. As the metal island films not only have large absorption but also high reflectance at the resonance wavelength, these could be used instead of absorption and reflection layers of the CD-R. In this work, we have successfully demonstrated preliminary experiments for CD-R type optical data storage media using metal island films. It has been experimentally confirmed that clear marks were formed by focused laser beam irradiation. We also discussed the application of the proposed optical data storage media using metal island films to the multiwavelength and multi-polarization optical disks.