| 빛을 가지고 컴퓨팅하는 기술의 발전 | ||||
| KISTI 미리안『글로벌동향브리핑』 2011-12-02 | ||||
최근 광학칩은 굉장히 많이 발전을 해오고 있다. 그래서 컴퓨터를 이용한 작업을 수행하기 위해서 전자 대신에 빔을 이용하는 기기들이 나오고 있다. 현재 MIT 연구자들은 현재 대부분의 전자공학에서 기초가 되고 있는 표준 실리콘 물질 위에 광학칩을 만들 수 있는 중요한 발전의 중심에 서게 되었다. 현재 많은 통신시스템에서 데이터는 광섬유를 통해서 전달되어진 빔의 형태로 전송된다. 광학 신호가 목적지에 도착하게 되면 이것은 전자적인 형태로 변환하게 되어, 전기 회로에서 처리되고 레이저를 사용한 빛으로 다시 전환되게 된다. 새로운 기기는 이러한 추가적인 전자 변환 과정을 없도록 하여 빛 신호가 바로 처리될 수 있도록 하였다. 새로운 구성요소는 “빛을 위한 다이오드(diode for light)”라고 MIT의 재료과학 및 공학과 Caroline Ross 교수가 말했다. 그녀는 11월 13일에 Nature Photonics 온라인 저널에 실리게 될 새로운 기기에 대한 논문의 공동저자이다. 이것은 전자 다이오드와 유사한 것으로서 전류가 한 방향으로 흐르며, 다른 방향으로 진행되어 흐르는 것을 차단해주는 기기이다. 이러한 경우에, 전기보다는 빛을 위한 한 방향 경로를 만들게 된다. 이러한 기기가 없다면, 반사 미광(stray reflections)이 광학신호를 만들기 위해서 사용되어지는 레이저를 불안정하게 만들 것이며, 전송 효율을 감소시킬 것이기 때문에 필수적이라고 Ross가 설명했다. 현재 아이솔레이터라는 이산기기는 이러한 기능을 수행하는데 사용되고 있다. 그러나 새로운 시스템은 다른 신호처리 작업을 하는 동일한 칩의 일부분에서 이러한 기능들을 하고 있다. 이 기기를 개발하기 위해서, 연구자들은 같이 발생하지 않는 두 가지 특징인 투명성과 자기성을 가진 물질을 개발해야만 한다. 그들은 석류석(garnet)이라는 물질의 형태를 사용하게 되었다. 이것은 일반적으로 마이크로칩에 사용되는 실리콘 웨이퍼 위에 성장하는 것이 어렵다. 그러나 석류석은 본질적으로 한 방향으로 빛을 전송하기 때문에 필수적이며 빔의 방향에 따라서 다른 굴절률을 가지게 된다. 연구자들은 칩 위의 빛 전달 채널을 연결하는 루프의 반을 덮기 위해서 석류석의 박막을 놓을 수 있다. 한 방향으로 칩을 따라서 움직이는 빛은 자유롭게 통과할 수 있으며, 다른 방향으로 진행하는 빔은 루프를 전환할 수 있게 된다는 결과를 얻게 되었다. 전체 시스템은 표준 마이크로칩 제조기계를 사용하여 만들 수 있다. “모든 광학칩에서 만드는 것은 단순하다.” 라고 Ross가 말했다. 회로의 디자인은 통합회로와 같이 만들 수 있기 때문에 전체 마이크로 프로세서를 디자인할 수 있으며 현재 당신은 통합된 광학 회로를 만들 수 있다고 그녀가 말했다. 다른 재료들에 기초한 시스템보다 이것을 상업화하는 것이 더 쉽다고 Ross가 말했다. “당신이 사용하고 싶은 것은 실리콘 플랫폼이다. 왜냐하면 실리콘 처리를 위한 거대한 인프라가 있기 때문이다. 모든 사람들은 실리콘을 어떻게 처리하는지 알고 있다. 즉, 새로운 제조기술에 대한 것을 걱정하지 않고도 칩을 개발할 수 있다는 것을 의미하는 것이다.” 라고 그녀가 말했다. 이 기술은 데이터 전송시스템의 속도를 많이 높일 수 있다. 그 이유 중 첫 번째는 전자보다 더 빠르게 빛이 움직인다는 것이며, 두 번째는 와이어가 하나의 전자적인 데이터 스트림만을 전송할 수 있지만, 광학 컴퓨팅은 많은 빔들을 전송할 수 있다. 그래서 단일 광학섬유를 통해서, 또는 간섭 없이도 분리된 데이터 스트림을 전송할 수 있게 해준다. 이것은 차세대 통신 시스템의 속도를 높여줄 수 있다고 Ross가 말했다. 연구를 같이 진행한 동료들은 Lionel Kimerling, Thomas Lord 교수 및 학생 Lei Bi, Juejun Hu 등이 있다. 이 연구는 국립과학재단(National Science Foundation)과 인텔사의 지원을 받아서 진행되었다. “이것은 광학통신의 큰 발전을 이룬 것이다.” 라고 Minnesota대학의 전기 및 컴퓨터공학과 Bethanie Stadler 교수가 말했다. 그리고 이 연구는 석류석이 실리콘 기기위에 통합되어진 첫 번째 기기로서 중요한 결과를 이룬 것이라고 덧붙였다.
|
Important step toward computing with light
Research at MIT produces long-sought component to allow complete optical circuits on silicon chips.
There has been enormous progress in recent years toward the development of photonic chips — devices that use light beams instead of electrons to carry out their computational tasks. Now, researchers at MIT have filled in a crucial piece of the puzzle that could enable the creation of photonic chips on the standard silicon material that forms the basis for most of today’s electronics.
In many of today’s communication systems, data travels via light beams transmitted through optical fibers. Once the optical signal arrives at its destination, it is converted to electronic form, processed through electronic circuits and then converted back to light using a laser. The new device could eliminate those extra electronic-conversion steps, allowing the light signal to be processed directly.
The new component is a “diode for light,” says Caroline Ross, the Toyota Professor of Materials Science and Engineering at MIT, who is co-author of a paper reporting the new device that was published online Nov. 13 in the journal Nature Photonics. It is analogous to an electronic diode, a device that allows an electric current to flow in one direction but blocks it from going the other way; in this case, it creates a one-way street for light, rather than electricity.
This is essential, Ross explains, because without such a device stray reflections could destabilize the lasers used to produce the optical signals and reduce the efficiency of the transmission. Currently, a discrete device called an isolator is used to perform this function, but the new system would allow this function to be part of the same chip that carries out other signal-processing tasks.
To develop the device, the researchers had to find a material that is both transparent and magnetic — two characteristics that rarely occur together. They ended up using a form of a material called garnet, which is normally difficult to grow on the silicon wafers used for microchips. Garnet is desirable because it inherently transmits light differently in one direction than in another: It has a different index of refraction — the bending of light as it enters the material — depending on the direction of the beam.
The researchers were able to deposit a thin film of garnet to cover one half of a loop connected to a light-transmitting channel on the chip. The result was that light traveling through the chip in one direction passes freely, while a beam going the other way gets diverted into the loop.
The whole system could be made using standard microchip manufacturing machinery, Ross says. “It simplifies making an all-optical chip,” she says. The design of the circuit can be produced “just like an integrated-circuit person can design a whole microprocessor. Now, you can do an integrated optical circuit.”
That could make it much easier to commercialize than a system based on different materials, Ross says. “A silicon platform is what you want to use,” she says, because “there’s a huge infrastructure for silicon processing. Everyone knows how to process silicon. That means they can set about developing the chip without having to worry about new fabrication techniques.”
This technology could greatly boost the speed of data-transmission systems, for two reasons: First, light travels much faster than electrons. Second, while wires can only carry a single electronic data stream, optical computing enables multiple beams of light, carrying separate streams of data, to pass through a single optical fiber or circuit without interference. “This may be the next generation in terms of speed” for communications systems, Ross says.
Ross’ colleagues in the research included Lionel Kimerling, the Thomas Lord Professor of Materials Science and Engineering, and former students Lei Bi ’11 and Juejun Hu PhD ’09. The work was funded by the National Science Foundation and an Intel fellowship for Bi.
“This is a big advance in optical communications,” says Bethanie Stadler, a professor of electrical and computer engineering at the University of Minnesota, who was not involved in this research. The work is “significant,” she says, “as the first device with garnet integrated onto [silicon] devices.”
In many of today’s communication systems, data travels via light beams transmitted through optical fibers. Once the optical signal arrives at its destination, it is converted to electronic form, processed through electronic circuits and then converted back to light using a laser. The new device could eliminate those extra electronic-conversion steps, allowing the light signal to be processed directly.
The new component is a “diode for light,” says Caroline Ross, the Toyota Professor of Materials Science and Engineering at MIT, who is co-author of a paper reporting the new device that was published online Nov. 13 in the journal Nature Photonics. It is analogous to an electronic diode, a device that allows an electric current to flow in one direction but blocks it from going the other way; in this case, it creates a one-way street for light, rather than electricity.
This is essential, Ross explains, because without such a device stray reflections could destabilize the lasers used to produce the optical signals and reduce the efficiency of the transmission. Currently, a discrete device called an isolator is used to perform this function, but the new system would allow this function to be part of the same chip that carries out other signal-processing tasks.
To develop the device, the researchers had to find a material that is both transparent and magnetic — two characteristics that rarely occur together. They ended up using a form of a material called garnet, which is normally difficult to grow on the silicon wafers used for microchips. Garnet is desirable because it inherently transmits light differently in one direction than in another: It has a different index of refraction — the bending of light as it enters the material — depending on the direction of the beam.
The researchers were able to deposit a thin film of garnet to cover one half of a loop connected to a light-transmitting channel on the chip. The result was that light traveling through the chip in one direction passes freely, while a beam going the other way gets diverted into the loop.
The whole system could be made using standard microchip manufacturing machinery, Ross says. “It simplifies making an all-optical chip,” she says. The design of the circuit can be produced “just like an integrated-circuit person can design a whole microprocessor. Now, you can do an integrated optical circuit.”
That could make it much easier to commercialize than a system based on different materials, Ross says. “A silicon platform is what you want to use,” she says, because “there’s a huge infrastructure for silicon processing. Everyone knows how to process silicon. That means they can set about developing the chip without having to worry about new fabrication techniques.”
This technology could greatly boost the speed of data-transmission systems, for two reasons: First, light travels much faster than electrons. Second, while wires can only carry a single electronic data stream, optical computing enables multiple beams of light, carrying separate streams of data, to pass through a single optical fiber or circuit without interference. “This may be the next generation in terms of speed” for communications systems, Ross says.
Ross’ colleagues in the research included Lionel Kimerling, the Thomas Lord Professor of Materials Science and Engineering, and former students Lei Bi ’11 and Juejun Hu PhD ’09. The work was funded by the National Science Foundation and an Intel fellowship for Bi.
“This is a big advance in optical communications,” says Bethanie Stadler, a professor of electrical and computer engineering at the University of Minnesota, who was not involved in this research. The work is “significant,” she says, “as the first device with garnet integrated onto [silicon] devices.”
댓글 없음:
댓글 쓰기