Development of Ultra-high Density Three-dimensional Optical Data storage System

光学数据存储系统，如CD和DVD，现在被广泛使用。然而，目前这种存储系统的容量不足以保证高质量的电影记录，即使存储密度几乎达到理论极限。因此，需要一种新的数据存储系统。我们开发了以二氧化硅为记录材料的三维（3D）光学数据存储系统，并明确了以下几点：1。通过皮秒或飞秒单脉冲辐照，通过多光子过程在一个小域（称为“位”）内引起反射率的变化。利用这种效果，可以构建三维数据存储系统。产生一个比特的时间周期大约是400ps。在钻头的中心产生了一个小凹。钻头非常热稳定；经1150度退火后，光学显微镜图像无变化。这些比特显示出特定的发光光谱。热退火降低了发光强度；在500度退火后，其发光性能几乎丧失。对于多层记录的样品，通过透射和发光图像分别独立读取每一层。在PMMA等其他材料中，也发现了同样的效果。

Optical data storage systems, such as CD and DVD, are now widely used. However, capacity of such currently available storage systems are not enough for recording movies in a high-quality even the storage densities are almost reaching to the theoretical limit. Accordingly a new data storage system is required. We have developed three-dimensional (3D) optical data storage system using silica as recording material, and clarified the following points :1. By irradiation of picosecond or femtosecond single pulse, a change in reflactive index is induced in a small domain (reffered as "bit") through a multiphoton process. Using such an effect, a three-dimensional data storage system can be constructed.2. The time-period to generate a bit was about 400 ps.3. A small hollow was generated at the center of the bit.4. The bits are thermally stable extremely ; by annealing at 1150 degree no change was induced in optical microscope image.5. The bits showed a specific luminescence spectra. The luminescence intensity was reduced by thermal annealing ; by annealing at 500 degree the luminescent property was almost lost.6. For multi-layer recorded samples, each layer was independently read by both transmission and luminescence images.7. In the other materials such as PMMA, the same effect was found.