ISSUE

JAN MAR 2009 MICA (P) No.: 163/08/2008 • a quarterly publication of Data Storage Institute

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Director’s Message

Nitto Denko collaborates with DSI n

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Multilayer Microholographic Data Storage n

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DSI Exhibits in FusionWorld

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Quantum Optics

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DSI SAB members paid a visit to Fusionopolis n

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A*STAR RI Open House

DSI holographic technology showcased at SIGGRAPH n

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06 Our Invited Speakers

n Recent Conferences/ Seminars/ Workshops Participated in by Our Staff

Director’s Message Looking back, 2008 has gone by very quickly, yet there were many memorable things about it, such as the opening of Fusionopolis, DSI’s future home. I was also very pleased that our SAB members could come and join us for such a momentous occasion. Fusionopolis is a science and technology epicenter that brings together researchers from different disciplines in the public and private sector to advance technology for the creation of a better world and future. The recent opening of Nitto Denko’s second R&D center at Fusionopolis and signing an agreement with us is a prime example of this in action. It also ties in closely with DSI’s vision of being a vital node in the global community and working with strategic partners to conduct world class R&D in next generation technologies. Also in line with the vision of Fusionopolis, an institution-wide open house was conducted to allow researchers from different institutes to visit any research institute (RI) of their interest. This was done in order to promote more opportunities for multi-disciplinary research and collaborative efforts amongst the RIs through a mutual understanding of each RI’s capabilities. A good example of such multi-disciplinary research in action is the research being done by our A*STAR Investigator, Dr Leonid Krivitsky. He is currently pioneering research in the area of Quantum Optics and Quantum Information and is working in collaboration with the Singapore Eye Research Institute (SERI). Through his research, we may be able to understand the fundamental workings of the eye and link this back to how our eyes transfer data to our brain which processes and stores it, much like a computer. Lastly, I would like to highlight FusionWorld, a gallery that showcases the science and engineering technologies of A*STAR. In this issue, we would briefly describe some DSI technologies that are being showcased there. I hope you will enjoy the articles in this issue and let me wish you all a Happy 2009!

Warmest Regards Professor Chong Tow Chong Executive Director

Nitto Denko collaborates with DSI

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itto Denko and DSI signed an agreement on 26 November 2008 to embark on research collaborations focused on the development of novel organic electronic sensing devices. Nitto Denko also established its second R&D centre in Singapore to be closer to their partners, The Nitto Denko Asia Technical Centre opened on the same day at Fusionopolis. Two other agreements linked with the development of organic electronics were also signed with A*STAR Institute of Materials Research and Engineering; and Nanyang Technological University.

Prof Chong Tow Chong, Executive Director of DSI and Dr Yasuo Fujimura, Managing Director, Nitto Denko Asia Technical Centre.

Organic electronics are plastic or carbon-based polymer electronics has been identified by Economic Development Board as a new growth area for the electronics industry and its uses span from healthcare to electronics and environmental-related industries.

A research institute of the Agency for Science, Technology and Research (A*STAR)

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Editorial Blu-ray technology is currently the market dominant for high density optical storage. Nonetheless, there is much research ongoing that aims to increase storage capacity beyond Blu-ray. One such alternative is multilayer microholographic data storage, which has been

deemed as one of the best candidates for nextgeneration high capacity optical data storage. At DSI, research is being conducted to even further increase the storage capacity of microholographic discs. Using a hybrid

multiplexing method, the number of layers that can be added to a recording material of 300µm thickness can be increased, thus increasing storage capacity.

Multilayer Microholographic Data Storage By Xu Xuewu, Sanjeev Solanki, Liang Xinan, Li Minghua, and Chong Tow-Chong Optical Materials and Systems Division

Introduction

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onventional optical data storage has successfully increased its storage capacity by using shorter wavelength laser and higher Numerical Aperture (NA) optics, from CD (780nm/0.45NA) to DVD (650nm/0.6NA) to Blu-ray disc (405nm/0.85NA). Beyond Blu-ray to further increase the capacity, one direction is to break the light diffraction limit to create smaller pit marks by using various near-field recording techniques. The other direction is to use the third dimension of a recording medium in addition to its 2D surface, i.e. so-called optical volumetric recording. Various volumetric recording technologies are currently at different R&D stages with growing technical interest, which include multilayer Bluray discs, bit-based multilayer microholographic storage, page-based holographic storage. Multilayer storage is a simple way to increase the capacity of a disc just by increasing the number of layers. Blu-ray based multilayer system might be able to achieve four to eight layers offering up to 200 GB per disc. But the number of layers is strongly limited by interlayer crosstalk, multiple reflection, high optical power requirement and disc manufacturing difficulty. Page-based holographic storage records the information in page format as 2D binary data through volume with a theoretical limit up to 116 Tb/in2 (1.5 mm thickness). Various systems based on 2-axis or coaxial holography are currently at the stage of development in many companies such as InPhase and Sony, and Toyohashi University of Technology, etc. Page-oriented holographic storage systems hold the top promise in achieving both large capacity (>1TB per disc) and high data transfer rate (>1Gbps). The cost of these systems is relatively high at the moment as they need new components such as Spatial Light Modulator (SLM) for data input, Complementary Metal–Oxide–Semiconductor (CMOS) detector for data retrieval and tunable blue laser diode for data recording/readout and temperature compensation.

Multilayer microholographic recording Bit-based multilayer microholographic storage is one of the best candidates for next-generation

high capacity optical data storage, especially for the applications that need a storage capacity of 200GB - 1TB per disc and a data transfer rate of up to 1 Gbps. In this approach, reflective microholographic volume gratings (microholograms) instead of pits are recorded by the interference between two counter-propagating laser beams that are tightly focused inside photosensitive material (Figure 1). Depth multiplexing (multilayer) is employed to attain high recording density. During readout the microhologram reflects the read beam and reconstructs the signal beam. This technology is currently at the R&D stage in companies such as Sony, GE and Samsung as well as Technical University of Berlin, etc. Bit-based multilayer microholographic storage system has the following features and advantages: • Compact and robust system design with downward compatibility • Most components in common with bitbased DVD pickup heads (no SLM, no CMOS) • Similar manufacturing technologies using existing DVD technology • Removable media without any physical spacing layers in a single homogenous recording material (e.g. photopolymer) • Hybrid multiplexing of microholograms with Bragg-selectivity • Wide media tilt tolerance as compared with page-based holographic storage system

New hybrid multiplexing method to increase storage capacity The overall storage capacity of a multilayer microholographic disc depends on the shift selectivity Δx, Δy and Δz of microholograms along x, y and z directions, respectively. Usually, the diameter (D) and length (L) of a reflective microhologram can be defined by the following equations:

(1)



(2)

where λ is the laser wavelength, NA is the numerical aperture of the objective lens, and n is the refractive index of the recording material.

Figure 1. Sketch of microholographic recording setup.

Microholograms that are as small as 0.3 μm in diameter can be recorded in a photopolymer medium with optimized recording conditions. For a recording material with a fixed thickness, e.g. 300 µm, the smaller the Δz is, the larger the number of data layers can be recorded. At Data Storage Institute (DSI), we have implemented random phase-coded 3D-shift multiplexing with highly focused spherical signal-reference beams in our reflection-type holographic recording setup and the shift selectivity of Δx = 1.5 µm, Δy = 5 µm and Δz = 5 µm has been achieved in our rewritable crystal media along x, y and z directions, respectively (Figure 2). In order to further increase the recording density, polarization of random phase-coded reference beam has been utilized in hologram multiplexing. Figure 3 shows the polarization selectivity measured by rotating the angle (θ) of a half-wave plate placed in the reference beam. When θ = 0° or 90°, the polarization of the reference beam is parallel to that of the signal beam, where the hologram is recorded. But when θ = 45°, the polarization of the reference beam is perpendicular to that of the signal beam and the previously recorded hologram cannot be read out. However, under this condition, the second hologram can be recorded at same location with the cross polarization of the reference beam by keeping the polarization

The shift selectivity has also been reduced by half by recording holograms alternately with the cross polarization of reference beam. This new hybrid multiplexing method can be used to increase the number of layers by further reducing the layer-to-layer spacing, Δz. Another important issue of bit-based multilayer microholographic storage

y (µm) technology is the data transfer rate limited by its bit-by-bit recording approach. To achieve a high data rate like 1Gbps, many problems and possible solutions for both the media and systems remain to be explored. Through experimentations, it was found that multi-beam recording and readout with lens arrays could significantly increase the data write/ read speed, however, this research is still ongoing.

z (µm)

Figure 3. Polarization selectivity of phase-coded reference beam.

DSI Exhibits in FusionWorld

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ith the inauguration of Fusionopolis, FusionWorld, a multi-sensory and interactive gallery was also opened to showcase A*STAR’s various science and engineering technologies. Many of these technologies have been used to help local enterprises move up the value chain.

Besides showcasing our technologies, another aim of FusionWorld is to expose the public, especially youths, to technologies that have impacts in their daily lives and hopefully inspire them to cultivate an interest in science. Five DSI technologies were showcased in the FusionWorld gallery. They are: • Wireless Hard Disk Drive (Wi-Drive) • A*Star Intelligent Media (A*IM) • In-Vehicle Event Monitoring System (IVEMS) • Micro-Motor Technology • Hard Disk Drive (HDD) Technologies

a single hard disk and multiple-access to the disk without the use of wires.

A*IM prototype

The A*STAR Intelligent Media (A*IM) is a prototype platform that can provide backup of personal digital data from disparate personal devices and stream the information from one device to another wirelessly. The In-Vehicle Event Monitoring System (IVEMS) is a device that includes up to six refined cameras positioned around the car to monitor events occurring around the car. With a hybrid disk storage system, it has a large storage

θ

capacity and even shocks on the road do not deter the device from continual recording. The Micro-Motor technology is actually a high performance miniature spindle motor that incorporates high speed with a compact Micro-Motor prototypes structure. With this technology, measurement instruments such as the Precision Vision Run-out Measuring System with Interference Technology and All-in-One Motor Tester were introduced, allowing sub-nano level measurements to be carried out with ease and accuracy. Hard Disk Drive (HDD) technologies include many aspects such as slider technology towards 2.5 nanometers flying-height, magnetic RAM technology (MRAM) and lubricant technology, just to name a few.

Suspension and HGA Spindle Motor

WiDrive – WiFi Storage

The Wi-Drive is a WiFi-enabled hard disk drive storage that allows multiple WiFi connectivity to

Diffraction (arb.)

x (µm) of signal beam unchanged. The reason why this can be done is mainly because both the reference and signal beams are tightly focused.

Figure 2. Measured 3D shift selectivity: Δx = 1.5 µm Δy = 5 µm Δz = 5 µm

Diffraction (arb.)

Diffraction (arb.)

Diffraction (arb.)

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Black box for automobiles

For those who are interested in visiting the FusionWorld gallery, please drop us an email at [email protected].

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Quantum Optics D r Leonid Krivitsky is a winner of the A*STAR Investigatorship award. The award supports and promotes the early independent career development of potential leaders in biomedical science, physical science and engineering research. Dr Krivitsky joined DSI in September 2008 to pioneer research in the field of Quantum Optics and Quantum Information. Below is a brief description of his research at DSI. How quantum is our vision? By Leonid Krivitsky Human eye represents a unique solution for the visual perception that developed with millions of years of evolution. Going into the details of eye operation you are amazed by how perfect and well organized this complex system is. Not surprisingly, there are many efforts in biomedical research invested in studying the different aspects of visual perception, to understand the fundamentals of vision and exploit this knowledge for treating eye diseases and diagnostics. Naturally, in order to recognize a certain problem with an eye, one should be able to characterize its response to light flashes with a precisely known intensity (the number of photons in a pulse) and compare it to the average characteristics over a specific group of people. The question arises: how do we get light flashes which always carry the same number of photons? Unfortunately, classical optics fundamentally prevents this opportunity due to the quantum nature of light. As a result, even perfectly stabilized laser will obey Poisson statistics for the number of emitted photons from pulse to pulse. This makes the characterization of an eye response very difficult and fundamentally uncertain.

Therefore, in order to perform eye diagnostics with the highest possible accuracy it is essential to manipulate light at a single photon level. This is why research on modern quantum optics that studies the counterintuitive quantum properties of light is being conducted here at the Quantum Optics lab at DSI. In collaboration with Singapore Eye Research Institute (SERI), we aim to build an apparatus that will provide an emission of a controllable number of photons and use it for the precise characterization of the photoreceptor response. As a result we aim to answer several fundamental questions, such as: What is the ability of our eye to detect a single photon? Do eye responses depend on different number of photons? What is the absolute quantum efficiency of an eye? The answers to these questions would lead to a precise characterization (at a truly quantum level!) of the performance of an eye and allow more accurate diagnostics and future treatment of eye diseases. From reading this article, the audience must be wondering how this research is connected with data storage. In order to answer this, another quite provocative question must be asked, namely: What is the most advanced computer ever created? The human brain is an obvious answer. From this viewpoint, our vision provides a critical link between the entire world and our brain, serving as a sort of information channel for the data transfer. Hopefully, in the far future, the progress of understanding the unique capabilities of the human brain will lead to a creation of an advanced biocomputer in which the perception channels would be considered as one of its essential part. Cognitive memory storage is a type of future memory which DSI is embarking research in. To learn more, please contact Data Storage Institute: [email protected]

DSI Staff published Special Issues Laser Ablation: Fundamentals

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elected materials of International Conference on Laser Ablation COLA 2007 (Tenerife, September 24-28, 2007) were recently published in Special Issue “Plasmonics” at Applied Physics A, vol. 92, Number 4, September 20, 2008. Guest Editors: B. S. Luk`yanchuk, S. Juodkazis and T. Lippert. The issue includes a paper by DSI staff.

Advances in Data Storage Systems and Technology DSI recently edited and published a special issue “Advances in Data Storage Systems and Technology” at the International Journal of Product Development,Vol. 5, Nos. 3/4, 2008. With a collection of 16 invited quality papers, the topics covered in this issue include nanomagnetics and high magnetic anisotropic media, nano-spintronics and magnetic read/write heads, nano-mechanics and ultra-low fly height technology, advanced signal processing and recovering, advanced system design and integration technology, and advanced optical data storage technology. The special issue is edited by Dr. Liu Bo (DSI), Dr. Jing Gui (Seagate Technology) and Dr. Zhao Jinmin (DSI).

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DSI SAB members paid a visit to Fusionopolis

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n October 2008, DSI’s Scientific Advisory Board (SAB) members flew in to Singapore to attend the Fusionopolis opening ceremony as well as the SERC SAB Forum. During their trip, DSI officers accompanied to Fusionopolis on a short tour. Whilst there, the SAB members also visited DSI’s Network Storage Technology (NST) division’s new offices and lab facilities in Fusionopolis. The SAB members would be returning in January 2009 for a meeting to review DSI’s technology roadmaps and research activities. Please visit our website for the detailed listings of our SAB members. SAB members at the sky garden in Fusionopolis.

A*STAR RI Open House

DSI holographic technology showcased at SIGGRAPH Examples of some reconstructed holographic 3D objects.

Dr Sanjeev Solanki conducting a lab tour.

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*STAR conducted its first RI Open House on 20 November 2008 following the A*STAR Scientific Conference held on 18 – 19 November 2008. The aim of this open house was to allow staff from other research institutes (RI) to obtain an overview of the research activities within the respective A*STAR RIs. DSI opened our session with an introduction of the Institute’s capabilities followed by lab tours.

OUR INVITED SPEAKERS

DSI staff explaining the concept of the holographic 3D display system.

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t the recent SIGGRAPH (Special Interest Group on Graphics and Interactive Techniques) Asia 2008, DSI showcased a holographic 3-dimensional display system under the A*STAR Home 2015 program. The system was developed by DSI and Institute of Infocomm Research (I2R). It allowed viewers to see reconstructed 3D objects either through a 2D display screen in virtual space or via a 3D display medium in real space.

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International NanoTechnological Revolution Workshop

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he 2008 NanoTechnological Revolution Workshop (NTR 2008) was held in Porquerolles Island, France from 5 - 11 October 2008.

Senior Scientist, Prof. Boris Lukiyanchuk, Senior Scientist participated in NTR 2008, where he introduced the lecture “Plasmon Resonances and Field Enhancement at Light Scattering by Spherical Particles with Radial Anisotropy”.The lecture given by Prof. Lukiyanchuk was devoted to the actual problem, related to field enhancement during optical excitation of localized plasmons in metallic particles. It was shown that radial anisotropy in material may lead to great modifications in scattering efficiencies and field enhancement, elucidating the importance of anisotropies in the scattering control.The ability of nondissipating damping was demonstrated for anisotropic spheres with different signs in radial and transversal permittivities.These effects are useful for Data Storage Technologies, e.g. for selection of perspective materials for next generation of optical recording. Prof. Andrey Fursenko (Minister of Education and Research of Russian Federation) - left, and Prof. Boris Lukiyanchuk (DSI, Singapore) at NTR 2008 on Porquerolles Island, France.

The NTR 2008 covers many interdisciplinary topics on nanotechnologies related to physics, chemistry and biology. Among the presented lectures were lectures on nanomaterials, applications in photonics and biomedicine, nanotechnology in life sciences and neurosciences, non-linear optics, semiconductor spintronics, photophoretic trapping of nanoparticles, etc.

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OUR INVITED SPEAKERS

International Conference on Electrical Machines and Systems

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he International Conference on Electrical Machines and Systems (ICEMS2008) was held in Wuhan, China from 17 - 20 October 2008.

Research Scientist Dr Bi Chao was invited to speak on ‘Influence of Transient current to PM AC Motor Driven by BLDC Mode’. Copper loss has been one of the major causes of power loss in PM BLDC motor operations. In his lecture, Dr Bi presented an analytic model that could help determine the optimal commutation angle (OCA) that would minimize the copper loss. Both simulations and testing results have proven the effectiveness of the model. The ICEMS2008 is a forum for researchers and professionals engaged in the field of electrical machines and drive systems to exchange their latest discoveries, trends and applications.

2nd International Workshop on Holographic Memories

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he 2nd International Workshop on Holographic Memories (IWHM 2008) was held in Aichi, Japan from 20 – 23 October 2008.

Pacific Rim Meeting on Electrochemical and Solid-state Science

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he Pacific Rim Meeting on Electrochemical and Solid-state Science (PRiME 2008) was held in Honolulu, Hawaii, USA from 12 - 17 October 2008.

Research Scientist, Dr Zhao Rong, was invited to give a lecture on “Phase Change Random Access Memory at 45 nm and beyond”.The lecture discussed the development and performance of PCRAM cells at nano-scale size. She also presented experimental results that showed a sample 128 bits 45 nanometer PCRAM array integrated with a 0.18 µm complementary metal–oxide– semiconductor (CMOS) demonstrating low current and good endurance of up to 108 cycles. PRiME 2008 is a joint international meeting that is held by The Electrochemical Society (ECS). It provides a forum for exchanging information on the latest scientific and technical developments in the fields of electrochemical and solidstate science and technology.

International Joint Tribology Conference

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he 2008 STLE/ASME International Joint Tribology Conference (IJTC 08) was held in Miami, Florida, USA from 20 - 22 October 2008.

Research Scientist, Dr Xu Xuewu was invited to give a talk on “Holography for Rewritable Data Storage and 3D Display”. Dr Xu shared the research work at Data Storage Institute Research Scientist Dr Xu Xuewu (right) with IWHM (DSI) on the various types Program Chair, Prof. Shimura, T. (University of Tokyo) of crystal media with nonvolatile rewritable data storage functionality and introduced their highspeed high-density holographic recording techniques. He also spoke on the recent joint effort between A*STAR, Institute for Infocomm Research (I2R) and DSI in developing a new holographic 3D display system. IWHM covers overall aspects on holographic memories ranging from their fundamental physics, chemistry, materials and recording technologies to practical system developments and applications including 3D display and 3D printer.

Dr Yu Shengkai, Senior Research Fellow, was invited to give a talk on “Inert Gas Filled Head-Disk Interface for Future Extremely High Density Magnetic Recording”. In his presentation, he shared the DSI’s investigation on the flying and thermal actuation performances of the Thermal Flying Height Control (TFC) sliders in inert gas filled Hard Disk Drives (HDDs). It was found that the environmental temperature effect on slider’s flying in a fully sealed drive is totally different from that in an open drive. In addition, no obvious obstacle was envisioned to use an inert gas sealed HDDs in practical applications from the viewpoint of slider flying. For more than 50 years, IJTC has been known as a pre-eminent platform that allows top tribology researchers from around the world, with differing backgrounds, be it, academia, industry or government agencies, to exchange ideas and knowledge. Continue on Page 5

Recent Conferences/ Seminars/ Workshops Participated in by Our Staff: Nanotechnological Revolution Workshop

2008 ASME International Mechanical Engineering Congress & Exposition

5 – 11 October 2008, Porquerolles Island, France

3 – 6 November 2008, Boston, USA

Pacific Rim Meeting on Electrochemical and Solid-state Science

53rd Annual Conference on Magnetism and Magnetic Materials

12 – 17 October 2008, Honolulu, USA

10 – 14 November 2008, Austin, Texas, USA

International Conference on Electrical Machines and Systems

IEEE Global Communications Conference 2008

17 – 20 October 2008, Wuhan, P.R. China

30 November – 4 December 2008, New Orleans, USA

International Workshop for Holographic Memories 2008 20 – 23 October 2008, Aichi, Japan

DSI Building, 5 Engineering Drive 1 (off Kent Ridge Crescent, NUS) Singapore 117608 Tel: 6874 6600 Fax: 6776 6527 Website: www.dsi.a-star.edu.sg