Download 8th International Symposium on Optical Storage/2008 International

8th International Symposium on Optical Storage/
2008 International Workshop on Information Data Storage
(ISOS/IWIDS 2008) in Wuhan (China)
The 8th International Symposium on Optical Data Storage took place in Wuhan, the capital of
Hubei province and center of the optics industry in China from November 24th to November
27th. It was organized by the Shanghai Institute of Optics and Fine Mechanics (Chinese
Academy of Sciences) and the Wuhan National Laboratory for Optoelectronics and was held
in conjunction with POEM 2008 (Photonics and Optoelectronics Meeting). The talks and
poster presentations gave an excellent overview over the present trends in optical data storage
and information storage in general and provided insight into the wide range of optical data
storage research in China. A number of invited talks in addition reviewed the status and the
perspectives in data storage with an emphasis on optical storage. A good overview over the
trends in the field was provided by a review presented by Masud Mansuripur (Tuscon,
Arizona) who addressed the question if future storage technologies can benefit from existing
or emerging nano-tools and techniques? He started his presentation by reviewing the property
portfolio and price range for different storage solutions. From this comparison he concluded
that hard disk drives face a tough competition from the recent fast advancement of solid state
memory. Third generation optical data storage projects are now becoming increasingly
widespread in the consumer market. Nevertheless the concomitant price tag might limit the
market penetration. Challenges were also seen for more advanced optical data storage
solutions due to the high price which would in the near future restrict this technology to highend applications and would exclude solutions in the field of consumer electronics. Regarding
novel non-volatile memories, Everspin (previously Freescale) offers an MRAM memory for
around 25 $, yet with a limited storage capacity of 4 Mbit. This led to the question how future
memory technologies can be inspired by advances in nanotechnology. Promising
developments were seen in the field of nanowire based memories. An overview of approaches
in this field has recently been published in Nature Materials 6, 841 (2007). Noteworthy is the
spin-off Nantero in Boston who develops carbon nanotube memories. Another interesting
development is pursued by IBM Almaden, where principal investigator Stuart Parkin works
with his team to develop a racetrack memory. While this memory should be attractive both in
terms of storage capacity and data transfer rate, production issues still arise, to create the
required three-dimensional nanostructures. A talk by Prof. Jimmy Zhu (Carnegie Mellon,
USA) reviewed recent advances in hard disk drive developments such as heat assisted
magnetic recording but also compared this technology with recent advances in FLASH
memory which have enabled this storage technology to enter the territory, which until
recently was solely occupied by hard disk drives. Finally alternative solid state memory
technologies such as spin torque transfer based magnetic RAM were presented. Advances in
optical storage were discussed in a series of talks. The presentations focused on recent
attempts to increase the storage density in optical memories. There were reports both on
recent advancements in near-field optical storage and progress related to a better
understanding of the super-RENS effect (Prof. Tominaga, AIST, Tsukuba, Japan). In this talk
an in-depth understanding of atomic rearrangement processes was presented which should
provide an atomistic view of the phenomena that govern the super-RENS effect. Equally
noteworthy, Prof. Tsai (National Taiwan University) discussed plasmonic coupling effects
which enable the detection of structures smaller than the classical diffraction limit. Since it is
possible to produce sub-wavelength structures in materials which show for example a
nonlinear response with respect to temperature, techniques were emphasized that enable
reading structures below the diffraction limit. It was discussed which schemes could enable
super-resolution readout. Particular emphasis was put on phenomena utilizing plasmonic
effects. Dr. Mitsuhashi from Japan Science and Technology Agency (Tsukuba, Japan)
presented standardization activities under ISO/IEC JTC/SC 23 which discusses digitally
recorded media. Until 2008 3 billion optical drives have been sold and 20 billion optical disks
have entered the consumer market. At present the third generation optical storage medium
market (Blu-ray disk) expands as rapidly as the DVD market 10 years ago. These numbers
evidence the positive development of optical media. Nevertheless the annual storage density
growth rate is falling behind the 65% annual growth rate in removable HDD. Hence the
further development of optical disk drives is governed by the advancement of novel
applications with high definition TV and video games presently being the main driver. A
larger number of invited talks focused on phase change materials for memory applications,
with an emphasis on emerging non-volatile memories. M. Wuttig (RWTH Aachen) described
a first map for phase change materials. This map enables the identification of new phase
change materials based upon the material’s stoichiometry (Nature Materials 7, 972 (2008)).
Furthermore the map can be employed to predict property trends such as the strength of
resonant bonding (Nature Materials 7, 653 (2008)), the optical contrast between amorphous
and crystalline state and trends for the structure as well as the resistivity of the crystalline
state. Two further invited talks presented the advancement of phase change research in China.
Prof. Zhitang Song (State Key Laboratory of Functional Materials for Informatics, Laboratory
of Nanotechnology, Shanghai Institute of Microsystems and Information Technology,
Chinese Academy of Sciencs, Shanghai, China) presented recent progress of phase change
random access memories. He focused on new materials, in particular Te-free phase change
materials such as Sb doped Si and Ti doped Ge. In a presentation by Prof. Xiang Shui MIAO
(Department of Electronic Science and Technology, Huazhong University of Science and
Technology, Wuhan and Wuhan National Laboratory for Optoelectronics, Wuhan, China)
phase change materials for optical storage were discussed. Special emphasis was given to the
potential of superlattice phase change materials. In addition photolithography based on phase
change materials was discussed where the nonlinear response of the material to an applied
laser pulse in conjunction with subsequent etching enabled the creation of sub-wavelength
feature sizes. Finally an invited talk by Prof. Y.Y. Lin (School of Microelectronics and State
Key Lab of ASIC & System, Fudan University, Shanghai, China) reported on progress in
resistive RAM technology based on binary transition metal oxide thin films.
The conference was also linked with the launch of the NVD (national versatile disc). This
optical storage medium was developed based upon an initiative of the Chinese government
which felt that the present third generation of optical disk drives is restricted to a price range
that is difficult to meet for many consumers in China. This was seen as a market opportunity
for a less expensive optical disk and recorder format. The goal was hence defined to create a
less expensive storage system which is adequate for the display of high quality TV content.
To utilize less expensive components, red lasers were employed. The development was
supported both by the Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of
Sciences and the Wuhan National Laboratory for Optoelectronics. The format employs a red
laser (λ = 650 nm, NA = 0.65). The track pitch is 0.62 µm and the minimum pit length is
0.388 µm. With a dual layer disc a capacity of 12 MB is reached. The disk should be priced
significantly below the BD disk and also the recorder will be only 1/3 of the price of the BD
drive. This is possible since the laser drive is much simpler and hence less expensive. Also for
the recorder a smaller fraction of royalties has to be deduced since several recorder and disc
attributes are not covered by foreign patents. This was seen as crucial for the Chinese optical
data storage business where 130 companies are operating a total of 1000 production lines for
optical disks.