Optica
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Professor Kyoungsik Yu Receives the Young IT Engineer Award from IEEE and IEIE of Korea
Professor Kyoungsik Yu of KAIST’s Department of Electrical Engineering is the recipient of this year’s Young IT (Information Technology) Engineer Award that was co-hosted by the Institute of Electrical and Electronics Engineers (IEEE), the Institute of Electronics Engineers of Korea (IEIE), and Haedong Science Culture Foundation in Korea. The award was presented on June 22, 2015 at The Ramada Plaza Jeju Hotel on Jeju Island, Korea.
The Young IT Engineer Award is given to emerging scientists who have made significant contributions to the advancement of technology, society, environment, and creative education.
Professor Yu's main research interests are IT, energy, and imaging through miniaturization and integration of optoelectronic devices. His contribution to academic and technological development is reflected in his publication of more than 100 papers in international journals and conferences, which were cited over 2,200 times.
Professor Yu said, “I’m honored to receive this award and am encouraged by it. I also find the award meaningful because the United Nations has designated this year as the “International Year of Light and Light-based Technologies,” the field I have been involved in as a researcher.”
In addition to Korea, the IEEE has jointly hosted and presented this award to researchers in countries such as Chile, Ecuador, Peru, Singapore, and Italy.
2015.06.22 View 10023 -
Fast, Accurate 3D Imaging to Track Optically-Trapped Particles
KAIST researchers published an article on the development of a novel technique to precisely track the 3-D positions of optically-trapped particles having complicated geometry in high speed in the April 2015 issue of Optica.
Optical tweezers have been used as an invaluable tool for exerting micro-scale force on microscopic particles and manipulating three-dimensional (3-D) positions of particles. Optical tweezers employ a tightly-focused laser whose beam diameter is smaller than one micrometer (1/100 of hair thickness), which generates attractive force on neighboring microscopic particles moving toward the beam focus. Controlling the positions of the beam focus enabled researchers to hold the particles and move them freely to other locations so they coined the name “optical tweezers.”
To locate the optically-trapped particles by a laser beam, optical microscopes have usually been employed. Optical microscopes measure light signals scattered by the optically-trapped microscopic particles and the positions of the particles in two dimensions. However, it was difficult to quantify the particles’ precise positions along the optic axis, the direction of the beam, from a single image, which is analogous to the difficulty of determining the front and rear positions of objects when closing an eye due to a lack of depth perception. Furthermore, it became more difficult to measure precisely 3-D positions of particles when scattered light signals were distorted by optically-trapped particles having complicated shapes or other particles occlude the target object along the optic axis.
Professor YongKeun Park and his research team in the Department of Physics at the Korea Advanced Institute of Science and Technology (KAIST) employed an optical diffraction tomography (ODT) technique to measure 3-D positions of optically-trapped particles in high speed. The principle of ODT is similar to X-ray CT imaging commonly used in hospitals for visualizing the internal organs of patients. Like X-ray CT imaging, which takes several images from various illumination angles, ODT measures 3-D images of optically-trapped particles by illuminating them with a laser beam in various incidence angles.
The KAIST team used optical tweezers to trap a glass bead with a diameter of 2 micrometers, and moved the bead toward a white blood cell having complicated internal structures. The team measured the 3-D dynamics of the white blood cell as it responded to an approaching glass bead via ODT in the high acquisition rate of 60 images per second. Since the white blood cell screens the glass bead along an optic axis, a conventionally-used optical microscope could not determine the 3-D positions of the glass bead. In contrast, the present method employing ODT localized the 3-D positions of the bead precisely as well as measured the composition of the internal materials of the bead and the white blood cell simultaneously.
Professor Park said, “Our technique has the advantage of measuring the 3-D positions and internal structures of optically-trapped particles in high speed without labelling exogenous fluorescent agents and can be applied in various fields including physics, optics, nanotechnology, and medical science.”
Kyoohyun Kim, the lead author of this paper (“Simultaneous 3D Visualization and Position Tracking of Optically Trapped Particles Using Optical Diffraction Tomography”), added, “This ODT technique can also apply to cellular-level surgeries where optical tweezers are used to manipulate intracellular organelles and to display in real time and in 3-D the images of the reaction of the cell membrane and nucleus during the operation or monitoring the recovery process of the cells from the surgery.”
The research results were published as the cover article in the April 2014 issue of Optica, the newest journal launched last year by the Optical Society of America (OSA) for rapid dissemination of high-impact results related to optics.
Figure 1: This picture shows the concept image of tweezing an optically-trapped glass bead on the cellular membrane of a white blood cell.
Figure 2: High-speed 3-D images produced from optical diffraction tomography technique
2015.04.24 View 11358 -
Extracting Light from Graphite: Core Technology of Graphene Quantum Dots Display Developed
Professor Seokwoo Jeon of the Department of Materials Science and Engineering, Professor Yong-Hoon Cho of the Department of Physics, and Professor Seunghyup Yoo of the Department of Electrical Engineering announced that they were able to develop topnotch graphene quantum dots from graphite.
Using the method of synthesizing graphite intercalation compound from graphite with salt and water, the research team developed graphene quantum dots in an ecofriendly way.
The quantum dots have a diameter of 5 nanometers with their sizes equal and yield high quantum efficiency. Unlike conventional quantum dots, they are not comprised of toxic materials such as lead or cadmium. As the quantum dots can be developed from materials which can be easily found in the nature, researchers look forward to putting these into mass production at low cost.
The research team also discovered a luminescence mechanism of graphene quantum dots and confirmed the possibility of commercial use by developing quantum dot light-emitting diodes with brightness of 1,000 cd/m2, which is greater than that of cellphone displays.
Professor Seokwoo Jeon said, “Although quantum dot LEDs have a lower luminous efficiency than existing ones, their luminescent property can be further improved” and emphasized that “using quantum dot displays will allow us to develop not only paper-thin displays but also flexible ones.”
Sponsored by Graphene Research Center in KAIST Institute for NanoCentury, the research finding was published online in the April 20th issue of Advanced Optical Materials.
Picture 1: Graphene quantum dots and their synthesis
Picture 2: Luminescence mechanism of graphene quantum dots
Picture 3: Structure of graphene quantum dots LED and its emission
2014.09.06 View 15920 -
SPIE (The International Society for Optics and Photonics): Scattering Super-lens
The International Society for Optics and Photonics (SPIE), dedicated to advancing an interdisciplinary approach to the science and application of light, published online a short paper authored by a KAIST research team, Dr. Jung-Hoon Park and Professor YongKeun Park of Physics, introducing a new optical technology to observe sub-wavelength light by exploiting multiple light scattering in complex media.
For the article, please go to the link below:
SPIE: Nanotechnology
May 7th, 2014
"Scattering superlens" by Jung-Hoon Park and YongKeun Park
http://spie.org/x108298.xml
2014.05.14 View 6716 -
The First Winner of Sang Soo Lee Award in Optics and Photonics
The Optical Society of Korea and the Optical Society of America selected Mario Garavaglia, a researcher at the La Plata Optical Research Center in Argentina, as the first winner of the Sang Soo Lee Award.
Dr. Garavaglia has been selected to receive the award in recognition for his research and education in the field of optics and photonics in Argentina.
The Sang Soo Lee Award, co-established by the Optical Society of Korea and the Optical Society of America in 2012, is awarded to an individual who has made a significant impact in the field. Special considerations are made for individuals who have introduced a new field of research, helped establish a new industry, or made a great contribution to education in the field.
The award is sponsored by the late Doctor Sang Soo Lee's family, the Optical Society of Korea, and the Optical Society of America.
The late Doctor Sang Soo Lee (1925~2010) has been widely known as the 'father of optics' in Korea. He was an active educator, researcher, and writer. Dr. Lee served as the first director of the Korea Advanced Institute of Science (KAIS), the predecessor to KAIST, which was Korea's first research oriented university.
Dr. Lee also served as the 6th president of KAIST between 1989 to 1991 and was a KAIST professor of physics for 21 years. He oversaw the completion of 50 Ph.D. and 100 Master's students as well as published 230 research papers.
Philip Bucksbaum, the president of the Optical Society of America, commented,
"Garavaglia has been an example to the spirit of the Sang Soo Lee Award. The award is the recognition for his tireless efforts and commitment to the development of optics and photonics in Argentina through his teaching, research, and publications."
Jeong-Won Woo, the president of the Optical Society of Korea, said,
"The Sang Soo Lee Award is given to researchers who have consistently contributed to the development of the field. Garavaglia is a well respected researcher in Argentina, and we are truly happy with his selection."
Dr. Garavaglia established a spectroscopy, optic, and laser laboratory in Universidad Nacional de La Plata in 1966. He founded the Center for Optical Research in 1977 and served as the chief of the laboratory until 1991.
Dr. Garavaglia published over 250 research papers in the fields of classical optics, modern optics, photoemission spectroscopy, and laser spectroscopy. He has also received the Galileo Galilei Award from the International Commission for Optics in 1999.
2014.03.31 View 9776 -
High Resolution 3D Blood Vessel Endoscope System Developed
Professor Wangyeol Oh of KAIST’s Mechanical Engineering Department has succeeded in developing an optical imaging endoscope system that employs an imaging velocity, which is up to 3.5 times faster than the previous systems. Furthermore, he has utilized this endoscope to acquire the world’s first high-resolution 3D images of the insides of in vivo blood vessel.
Professor Oh’s work is Korea’s first development of blood vessel endoscope system, possessing an imaging speed, resolution, imaging quality, and image-capture area. The system can also simultaneously perform a functional imaging, such as polarized imaging, which is advantageous for identifying the vulnerability of the blood vessel walls.
The Endoscopic Optical Coherence Tomography (OCT) System provides the highest resolution that is used to diagnose cardiovascular diseases, represented mainly by myocardial infarction.
However, the previous system was not fast enough to take images inside of the vessels, and therefore it was often impossible to accurately identify and analyze the vessel condition. To achieve an in vivo blood vessel optical imaging in clinical trials, the endoscope needed to be inserted, after which a clear liquid flows instantly, and pictures can be taken in only a few seconds.
The KAIST research team proposed a solution for such problem by developing a high-speed, high-resolution optical tomographic imaging system, a flexible endoscope with a diameter of 0.8 mm, as well as a device that can scan the imaging light within the blood vessels at high speed. Then, these devices were combined to visualize the internal structure of the vessel wall.
Using the developed system, the researchers were able to obtain high-resolution images of about 7 cm blood vessels of a rabbit’s aorta, which is similar size to human’s coronary arteries. The tomography scan took only 5.8 seconds, at a speed of 350 scans per second in all three directions with a resolution of 10~35㎛.
If the images are taken every 200 ㎛, like the currently available commercial vascular imaging endoscopes, a 7cm length vessel can be imaged in only one second.
Professor Wangyeol Oh said, “Our newly developed blood vessel endoscope system was tested by imaging a live animal’s blood vessels, which is similar to human blood vessels. The result was very successful.”
“Collaborating closely with hospitals, we are preparing to produce the imaging of an animal’s coronary arteries, which is similar in size to the human heart,” commented Professor Oh on the future clinical application and commercialization of the endoscope system. He added, “After such procedures, the technique can be applied in clinical patients within a few years.”
Professor Oh’s research was supported by the National Research Foundation of Korea and the Global Frontier Project by the Korean government. The research results were published in the 2014 January’s edition of Biomedical Optics Express.
Figure 1: End portion of optical endoscope (upper left)
Figure 2: High-speed optical scanning unit of the endoscope (top right)
Figure 3: High-resolution images of the inside of in vivo animal blood vessels (in the direction of vascular circumference and length)
Figure 4: High-resolution images of the inside of in vivo animal blood vessels (in the direction of the vein depth)
2014.03.25 View 10251 -
Seo-Eun Lee, an undergaruate student receives the Best Paper Award from Optical Society of Korea
Seo-Eun Lee, a student studying at KAIST’s Department of Biological Sciences, has won the Best Paper Award from Bio-Photonics Division at the 2014 Optical Society of Korea Winter Conference, held on 19th February at Daejeon Convention Center.
Only one outstanding paper per division is given an award among the total of 270 papers, and it is very unusual for an undergraduate student to win the award in the field that is not her major.
Lee has studied cell imaging using holography technology since June 2013 under the supervision of Professor Yong-Geun Park from the Department of Physics.
The Optical Society of Korea was founded in 1989, and as the largest academy in the field of optics in Korea, it holds academic presentations, seminars and lectures every year.
2014.03.06 View 9169 -
Green Technology for Data Centers: Ultra-low Power 100 Gbps Ethernet Integrated Circuit Developed
A new integrated circuit (IC), consuming only 0.75W of electricity, will reduce the power usage of data chips installed at data centers by one-third.
Each day, billions of people surf the Internet for information, entertainment, and educational content. The Internet contains an immeasurable amount of information and knowledge generated every minute all around the world that is readily available to everyone with a click of a computer mouse. The real magic of the Internet, however, lies in data centers, where hundreds of billions of data are stored and distributed to designated users around the clock.
Today, almost every business or organization either has its own data centers or outsources data center services to a third party. These centers house highly specialized equipment responsible for the support of computers, networks, data storage, and business security. Accordingly, the operational cost of data centers is tremendous because they consume a large amount of electricity.
Data centers can consume up to 100 times more energy than a standard office building. Data center energy consumption doubled from 2000 to 2006, reaching more than 60 billion kilowatt hours per year. If the current usage and technology trends continue, the energy consumption of data centers in the US will reach 8% of the country’s total electric power consumption by 2020.
A research team at the Korea Advanced Institute of Science and Technology (KAIST) and Terasquare, Inc. (
http://www.terasquare.co.kr
), a spin-off company of the university,
developed an extremely low-powered integrated circuit for Ethernet that consumes less than 0.75W of electricity but is able to send and receive data at the high speed of 100 gigabits per second (Gbps). The research team, headed by Hyeon-Min Bae, assistant professor of electrical engineering at KAIST, claims that the new microchip uses only one-third of the electricity consumed by the currently installed chips at data centers, thereby helping the centers to save energy.
Integrated circuits are embedded on communication modules that are inserted into a line card. Data centers have numerous line cards to build a network including routers and switches. Currently, 8W ICs are the most common in the market, and they consume a lot of energy and require the largest modules (112 cm
2
of CFP), decreasing the port density of line cards and, thus, limiting the amount of data transmission.
The ultra-low-power-circuit, 100-gigabit, full-transceiver CDR, is the world’s first solution that can be loaded to the smallest communication modules (20 cm
2
of CFP4 or 16 cm
2
of
QSFP28), the next-generation chips for data centers. Compared with other chip producers, the 100 Gbps CDR is a greener version of the technology that improves the energy efficiency of data centers while maintaining the high speed of data transmission.
Professor Hyeon-Min Bae said, “When we demonstrate our chip in September of this year at one of the leading companies that manufacture optical communication components and systems, they said that our product is two years ahead of those of our competitors. We plan to produce the chip from 2014 and expect that it will lead the 100 Gbps Ethernet IC market, which is expected to grow to USD 1 billion by 2017.”
The commercial model of the IC was first introduced at the 39
th
European Conference and Exhibition on Optical Communication (ECOC), the largest optical communication forum for new results and developments in Europe, held from September 22-26 at ExCeL London, an international exhibition and convention center.
Professor Bae added, “We received positive responses to our ultra-low-power 100-Gbps Ethernet IC at the ECOC. The chip will be used not only for a particular industry but also for many of next-generation, super-high-speed information communications technologies, such as high-speed USB, high-definition multimedia interface (HDMI), and TV interface.”
Before joining KAIST, Hyeon-Min Bae worked for many years at Finisar as a researcher who designed and developed the world’s first super-high-speed circuit, the 100 Gbps Ethernet IC.
2013.11.25 View 8501 -
New Technology Will Enable the Commercialization of Plasmon Displays
-- Enhancements in the penetration ratios of color filters are expected by applying nano-surface plasmon effects. --
-- Color filter technology will be applicable to large-area OLED and LCD. --
The fabrication technology to commercialize display color filters using plasmon effects has been discovered.
A joint research team headed by Professor Kyung Cheol Choi from the Department of Electrical Engineering of the Korea Advanced Institute for Science and Technology and Prof. Byeong-Kwon Ju from the School of Electrical Engineering of Korea University has developed the technology to design and produce a display color filter by applying nano-surface plasmon effects.
Color filters are core components used to express colors in CMOS image sensors found in LCD/OLED displays or digital cameras. The current color filters have penetration ratios of 20~30%, but the objective of the joint research team is to raise this penetration ratio by over 40% to facilitate the mass production of energy-efficient plasmonic displays.
Currently available plasmonic color filters are limited to applications on micrometer scales. However, outcomes of the newest research extend the size of the applications up to 2.5 cm by using laser interference lithography. The academic and industrial sectors agree that it is now possible to mass-produce displays using plasmonic color filters.
The researchers built a nanohole array to large scale by using laser interference lithography, a technology that forms nanostructures with laser light interferences. They also suggested a new manufacturing process that can optimize the features of color filters while compensating for defects arising from the fabrication stages.
The new manufacturing process of applying laser interference lithography is expected to overcome the shortcomings of traditional color filters by simplifying production and, enabling them to be produced at lower costs.
“There were limitations to industrial applications of plasmon effect due to production costs, time, and yields,” explained Yun Seon Do, a Ph. D. candidate in the Department of Electrical Engineering of KAIST. “The new technology can reduce fabrication time and cost to the extent that it would be advisable to replace dye-based and pigment-based color filter technology."
“This research can be applied to large-scale displays, such as TV screens, by using laser-interference lithography,” said Jung-Ho Park, a Ph. D. candidate in the School of Electrical Engineering of Korea University. “The research outcome is expected to be widely applied in advanced nano-manufacturing processes as it does not restrict the types of circuit boards."
The research outcome, led by doctoral candidates Do and Park, appeared on the front cover of the second issue of Advanced Optical Materials, a highly regarded academic journal in the field of nanotechnologies, and the team has applied for six related patents.
2013.03.13 View 8372 -
The control of light at the nano-level
Professor Min Bumki
Professor Min Bumki’s research team from the Department of Mechanical Engineering at KAIST have successfully gained control of the transmittance of light in optical devices using graphene* and artificial 2-dimensional metamaterials**.
* Graphene : a thin membrane composed of pure carbon, with atoms arranged in a regular hexagonal pattern
** Metamaterials : artificial materials engineered to have properties that may not be found in nature
The research results were published in the recent online edition (September 30th) of Nature Materials, a sister journal of the world renowned Nature journal, under the title ‘Terahertz waves with gate-controlled active graphene metamaterials’
Since the discovery of graphene in 2004 by Professors Novoselov and Geim from the University of Manchester (2010 Nobel Prize winners in Physics), it has been dubbed “the dream material” because of its outstanding physical properties.
Graphene has been especially praised for its ability to absorb approximately 2.3% of near infrared and visible rays due to its characteristic electron structure. This property allows graphene to be used as a transparent electrode, which is a vital electrical component used in touch screens and solar batteries. However, graphene’s optical transmittance was largely ignored by researchers due to its limited control using electrical methods and its small optical modulation in data transfer.
Professor Min’s team combined 0.34 nanometer-thick graphene with metamaterials to allow a more effective control of light transmittance and greater optical modulation. This graphene metamaterial can be integrated in to a thin and flexible macromolecule substrate which allows the control of transmittance using electric signals.
This research experimentally showed that graphene metamaterials can not only effective control optical transmittance, but can also be used in graphene optical memory devices using electrical hysteresis.
Professor Min said that “this research allows the effective control of light at the nanometer level” and that “this research will help in the development of microscopic optical modulators or memory disks”.
figure 1. The working drawing of graphene metamaterials
figure 2. Conceptual diagram (Left) and microscopic photo (right) of graphene metamaterials
2012.11.23 View 9901 -
Seeing Inside Cells with Fiber Optics
Professor Jiho Park’s research team was successful in receiving minute optical signals from inside the cell using optical nano fibers.
Through the invention of this technology, we can now look inside cells in high resolution without the use of equipment such as endoscopes that damage cells. We will be able to study the biological phenomena within cells, and thus cure diseases more effectively.
Recently, ultra high resolution microscopes have been used to analyze incubated cells. However, because of the need for a very complex and large system, it had been impossible to monitor cells in the less transparent areas of the body in real time.
The research team created the wire with a semiconductor created with tin oxides to be only 100 nanometers in diameter (1nanometer= 1/1billion meters).
The nanowire is connected to the end of the optical fiber, and the light that comes through the optical fiber is transmitted to particular spots in the cell, and the optical signals from the cell are retrieved back from the cell as well
Together with this, based on the fact that nanowires do not damage cells, the research team covered the end of the wire with a photo reactive material and entered this into the cell. They were able to check that the material reacted to light and entered the cell when they transmitted light
Accordingly, this showed the possibilities of the use of this technology as a method of treatment to effectively transfer the medication into the cells.
Prof. Jiho Park stated that “in this research, we only used cells incubated outside the human body, but soon we will use this technology to stimulate and control cells within the body in a minute scale” as well as that “soon, we will be able to study the biological phenomena inside a cell to study diseases and apply this to cure them more effectively”.
This research result has been published in the online publication of ‘Nature Nanotechnology’ on December 18.
This study was done through the cooperation of various schools. Besides Prof. Jiho Park, Prof. Seungman Yang from the Biochemistry department, and Doctor Chuljoon Huh from KAIST, Prof. Yeonho Choi from Biomedical Science department of Korea University, Professor Peidon Yang and Doctor Ruoxue Yan from UC Berkeley’s chemistry department, and Luke Lee from UC Berkeley’s bioengineering department participated in the project.
2012.01.31 View 9096 -
Professor Min Beom Ki develops metamaterial with high index of refraction
Korean research team was able to theoretically prove that a metamaterial with high index of refraction does exist and produced it experimentally.
Professor Min Beom Ki, Dr. Choi Moo Han, and Doctorate candidate Lee Seung Hoon was joined by Dr. Kang Kwang Yong’s team from ETRI, KAIST’s Professor Less Yong Hee’s team, and Seoul National University’s Professor Park Nam Kyu’s team. The research was funded by the Basic Research Support Program initiated by the Ministry of Education, Science, and Technology and Korea Research Federation.
The result of the research was published in ‘Nature’ magazine and is one of the few researches carried out by teams composed entirely of Koreans.
Metamaterials are materials that have physical properties beyond those materials’ properties that are found in nature. It is formed not with atoms, but with synthetic atoms which have smaller structures than wavelengths.
The optical and electromagnetic waves’ properties of metamaterials can be altered significantly which has caught the attention of scientists worldwide.
Professor Min Beom Ki’s team independently designed and created a dielectric metamaterial with high polarization and low diamagnetism with an index of refraction of 38.6, highest synthesized index value.
It is expected that the result of the experiment will help develop high resolution imaging system and ultra small, hyper sensitive optical devices.
2011.02.23 View 15489