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Optical Design & Engineering

Future memories

Eye on Technology - optical data storage

From oemagazine May 2002
30 May 2002, SPIE Newsroom. DOI: 10.1117/2.5200205.0003

Perceiving itself as being behind in the telecommunications and information industries, Japan has embarked on a catch-up program that aims at development of specific technologies according to broad timetables. Optical memory and data storage systems are among the critical technologies identified by Japan's Optoelectronic Industry and Technology Development Association (OITDA) for focused development efforts aimed at IT-integrated societies of the 2030s.

Analysts see Japan's population gradually declining from its peak at the turn of the century, and expect those over 65 will account for nearly 30% of the total population. Furthermore, say pundits, in Japan, the emphasis will no longer be on the basics of food, clothing, and shelter, but rather on the enjoyment of leisure time. The OITDA believes this is where information technology can play a significant role.

"The Ministry of Education, Science, Sports, and Culture (MEXT) has forecast a list of information technologies it expects to see commercialized in the next few decades, and they all show the need for a new generation of optical memory and data storage devices," says Ryoichi Imanaka, general manager at AVC Company of Matsushita Electric Industries Co. (Osaka, Japan). Some of the technologies MEXT expects include telephones that automatically interpret other languages for their users, digital television, video on demand, electronic libraries, 256 Gb large-scale integrated circuits, cleaning and laundry robots, cell phones with global roaming, and optical memory devices that operate at molecular and elemental levels.

Imanaka predicts that people in 2030 will have access to various databases from their homes. "We'll see most government services offered online—including voting," Imanaka says. "And most healthcare services will be available from home as well. Doctors will be able to use remote devices to test and diagnose patients, and nurses will take care of bedridden elderly by controlling in-home service robots." All of these technologies, says Imanaka, require massive data storage capacity.

By the 2030s, network speeds will probably be in the 1 Tb/s range, but Imanaka thinks that about 70% of Japanese households will be able to handle data speeds of about 1 Gb/s. How much storage will popular devices need in the future? Imanaka puts mobile device storage capacity at 100 GB, home server capacity at more than 100 TB, and regional cache servers at up to 100 PB. Archive disks will probably hold up to 1 TB of data each, says Imanaka.

Motoichi Ohtsu, a professor at the Tokyo Institute of Technology (Tokyo, Japan), throws in a word of caution. "Let us not forget," says Ohtsu, "that near-field optics represent a paradigm shift, and history tells us that it takes decades for the technology to come of age." Ohtsu points out that lasers were developed in the 1960s, but optical disk memory systems did not appear until the 1980s. The current goal for near-field optical storage is to achieve 1 Tb/in2 by 2010.

Optical disk systems that use near-field technology, use the near-field light generated at the tip of a probe to record, read, and erase data. The density of the data is determined by the size of the probe end and can be made very dense indeed. Ohtsu's research team is currently working on a recording device that makes 25 nm marks and reproduces the data with better than 40 dB carrier-to-noise ratio. "The 1 Tb/in2 goal for 2010 is firmly in sight," he says, noting that current work on nanophotonic devices will soon lead to methods of integrating them into devices that resemble current semiconductor memory chips only they will be chips that use near-field light and nanocircuits to construct their memories. Otsu's research group has already successfully demonstrated optical near-field switches as examples of nano-order integrated light circuits.

With these and other innovations, researchers and corporations in Japan are making steady progress toward high-density optical storage device goals outlined by OITDA's optical memory roadmap to 2030.