High density optical data storage using a medium which has photonic crystal structures

三维光存储器由于能够克服光波衍射所决定的密度限制而得到了许多研究人员的发展。为了增加轴向的密度，我们开发了一种多层记录介质，其中光敏薄膜和非光敏透明薄膜交替堆叠。由于光敏膜比记录光束的聚焦深度薄，记录钻头的空间频率分布在轴向扩展。我们已经开发了在记录介质中制造光子晶体结构，以实现更高的分辨率和对比度。在记录以六角形阵列的形式排列的情况下，结构化介质中记录比特的形状由聚焦光束的平方强度和图案介质的结构的乘积决定。其频率分布由光斑强度平方的频率分布与图案介质的频率分布的卷积得到。因此，图形介质中的每个比特包含更高的空间频率分量。我们成功地记录了特定平面上间隔0.5μm、连续层之间间隔2.0μm的比特。从而实现2.0Tbits/cm3的存储密度。

Three-dimensional optical memory has been developed by many researchers because it can overcome the density limit determined by the diffraction of light wave. In order to increase the density in the axial direction, we have developed a mltilayered recording medium in which photosensitive thin films and nonphotosensitive transparent films were stacked alternately. Since the photosensitive films were thinner than the depth of focus of the recording beam, the spatial frequency distribution of the recorded bit was extended in the axial direction. We have developed the fabrication of photonic crystal structures in the recording medium to achieve higher resolution and contrast.In the case of recording are arranged in the form of hexagonal arrays, the shape of a recorded bit in a structured medium is determined by the products of squared intensity of the focused beam and the structure of the patterned medium. Its frequency distribution is given by convolution of the frequency distribution of the squared spot intensity and that of the patterned medium. As a result, each individual bit in the patterned media contains higher spatial frequency components. We succeeded in recording bits with a 0.5μm interval in particular plane and 2.0μm interval between successive layers. Thus, storage density of 2.0Tbits/cm3 is achieved.