“Wisdom is not a product of schooling but of the lifelong attempt to acquire it”--Albert Einstein
Monday, February 02, 2015
Sunday, February 12, 2012
Electrical Engineers Build 'No-Waste' Laser
A team of University of California, San Diego researchers has built the smallest room-temperature nanolaser to date, as well as an even more startling device: a highly efficient, "thresholdless" laser that funnels all its photons into lasing, without any waste.
The two new lasers require very low power to operate, an important breakthrough since lasers usually require greater and greater "pump power" to begin lasing as they shrink to nano sizes. The small size and extremely low power of these nanolasers could make them very useful components for future optical circuits packed on to tiny computer chips, Mercedeh Khajavikhan and her UC San Diego Jacobs School of Engineering colleagues report in the Feb. 9 issue of the journal Nature.
They suggest that the thresholdless laser may also help researchers as they develop new metamaterials, artificially structured materials that are already being studied for applications from super-lenses that can be used to see individual viruses or DNA molecules to "cloaking" devices that bend light around an object to make it appear invisible.
All lasers require a certain amount of "pump power" from an outside source to begin emitting a coherent beam of light or "lasing," explained Yeshaiahu (Shaya) Fainman, a professor in the Department of Electrical and Computer Engineering at UC San Diego and co-author of the new study. A laser's threshold is the point where this coherent output is greater than any spontaneous emission produced.
The smaller a laser is, the greater the pump power needed to reach the point of lasing. To overcome this problem, the UC San Diego researchers developed a design for the new lasers that uses quantum electrodynamic effects in coaxial nanocavities to alleviate the threshold constraint. Like a coaxial cable hooked up to a television (only at a much smaller scale), the laser cavity consists of a metal rod enclosed by a ring of metal-coated, quantum wells of semiconductor material. Khajavikhan and the rest of the team built the thresholdless laser by modifying the geometry of this cavity.
The new design also allowed them to build the smallest room-temperature, continuous wave laser to date. The new room-temperature nanoscale coaxial laser is more than an order of magnitude smaller than their previous record smallest nanolaser published in Nature Photonics less than two years ago. The whole device is almost half a micron in diameter -- by comparison, the period at the end of this sentence is nearly 600 microns wide.
These highly efficient lasers would be useful in augmenting future computing chips with optical communications, where the lasers are used to establish communication links between distant points on the chip. Only a small amount of pump power would be required to reach lasing, reducing the number of photons needed to transmit information, said Fainman.
The nanolaser designs appear to be scalable -- meaning that they could be shrunk to even smaller sizes -- an extremely important feature that makes it possible to harvest laser light from even smaller nanoscale structures, the researchers note. This feature eventually could make them useful for creating and analyzing metamaterials with structures smaller than the wavelength of light currently emitted by the lasers.
Fainman said other applications for the new lasers could include tiny biochemical sensors or high-resolution displays, but the researchers are still working out the theory behind how these tiny lasers operate. They would also like to find a way to pump the lasers electrically instead of optically.
Co-authors for the Nature study, "Thresholdless Nanoscale Coaxial Lasers," include Mercedeh Khajavikhan, Aleksandar Simic, Michael Kats, Jin Hyoung Lee, Boris Slutsky, Amit Mizrahi, Vitaliy Lomakin, and Yeshaiahu Fainman in the Department of Electrical and Computer Engineering at the UC San Diego Jacobs School of Engineering. The nanolasers are fabricated at the university's NANO3 facility. The research was funded by the Defense Advanced Research Projects Agency, the National Science Foundation, the NSF Center for Integrated Access Networks (CIAN), the Cymer Corporation and the U.S.
Saturday, March 06, 2010
Sunday, October 25, 2009
Seeing Previously Invisible Molecules For The First Time
A team of Harvard chemists led by X. Sunney Xie has developed a new microscopic technique for seeing, in color, molecules with undetectable fluorescence. The room-temperature technique allows researchers to identify previously unseen molecules in living organisms and offers broad applications in biomedical imaging and research.
he scientists' results are published in the Oct. 22 issue of Nature. Partial funding for the project was provided by the National Science Foundation (NSF).
Fluorescence is a phenomenon in which an electron in a molecule absorbs energy from light and moves to a higher energy level or excited state. The energy of the light is contained in a unit called a photon.
Tuesday, February 06, 2007
Her us a good travel blog. nice photos lots of information..
Saturday, December 09, 2006
HD VMD - 40GB Multilayer Optical disc - It Costs a fraction of Blu Ray !!
The developer of a maverick high-density DVD format is planning to release a player that costs a fraction of the price of devices using the mainstream Blu-ray and HD-DVD formats.
London-based New Media Enterprises announced its Versatile Multi-layer Disc (VMD) format at Cebit earlier this year. It uses low-cost red lasers used in existing DVD players but, as its name suggests, can squeeze up to 40GB on a single disc by stacking the data at different levels. The player, launched at the Mipcom digital-content show in Cannes, will cost about $175 (£95), which compares very favourably with the competing formats.
Samsung’s BD-P1000 Blu-ray player has already debuted in the UK with a £1,000 price tag. Toshiba expects to have its HD-DVD players on the market in November and December, with the HD-E1 and HD-XE1 models costing €599 (around £400) and €899 (around £600) respectively.
However, New Media Enterprises’ product seems unlikely to dent the market for Blu-ray and HD-DVD players, because deals have already been signed with major Hollywood and European companies to sell titles in those formats. New Media Enterprises said at Cebit that it would initially target the Chinese and Bollywood markets – the latter, in particular, is very big in Britain. A spokeswoman for the company said that other content providers had shown interest and a deal with one German company is expected to be announced shortly. New Media Enterprises’ player will be available in some European countries in December, with availability throughout Europe in January.
Thursday, December 07, 2006
Mi-iraj, A miraculous journey..
A travel site there r so many links to top travel sites
You will find it interesting..
Wednesday, November 29, 2006
Massive Array of Idle Disks-MAID
MAID is an array of hard drives combined to work as a single point of storage. Scalability is therefore not an issue. At present the smallest of the Copan's available systems is 28 terabytes, nad the largest is 200 terabytes. The space used by the largest capacity array that Copan produces is just one suare metre, thus saving hume amount of space.
MAID will be used where there is a need to archive large amount of data scaling up in terabytes. It also provides quick access to large amount of data.
MAID consumes less power and hence produces less heat. This is possible becoz, when data is not accessed the harddisks go into idle mode thus making it more energy efficient. MAID allows the data storage in structured formats like SQL, MS Access and also in unstructured data formats like Word and Powerpoint.
This technology when becomes more dominant will soon replace the present hosting servers with lots of features and also we can find most of the data warehouse shifting to this new technology.
Saturday, November 18, 2006
Coming Soon Mobile Broadband Internet
In a move that could well be the beginning of Internet access through mobile Broadband, Hutchison Whampoa has forged a group of global Internet companies, and handset makers - Nokia and Sony Ericsson, to globally launch Broadband mobile Internet access on the same flat fee model as fixed Broadband Internet.
Titled "X-Series from 3," the service will include free Skype calling, unlimited Web browsing, and instant messaging from mobile handsets.
Monday, October 23, 2006
Prototype DNA computer ( MAYA-II)
Researchers say that they have developed a DNA-based computer that could lead to faster, more accurate tests for diagnosing West Nile Virus and bird flu. Representing the first “medium-scale integrated molecular circuit,” it is the most powerful computing device of its type to date, they say.
The new technology could be used in the future, perhaps in 5 to 10 years, to develop instruments that can simultaneously diagnose and treat cancer, diabetes or other diseases, according to a team of scientists at Columbia University Medical Center in New York and the University of New Mexico, Albuquerque. Their study is scheduled to appear in the November issue of the American Chemical Society’s Nano Letters, a monthly peer-reviewed journal.
“These DNA computers won’t compete with silicon computing in terms of speed, but their advantage is that they can be used in fluids, such as a sample of blood or in the body, and make decisions at the level of a single cell,” says the researcher, whose work is funded by the National Science Foundation.
Composed of more than 100 DNA circuits, MAYA-II is quadruple the size of its predecessor, MAYA-I, a similar DNA-based computer developed by the research team three-years ago. With limited moves, the first MAYA could only play an incomplete game of tic-tac-toe, the researcher says.
The experimental device looks nothing like today’s high-tech gaming consoles. MAYA-II consists of nine cell-culture wells arranged in a pattern that resembles a tic-tac-toe grid. Each well contains a solution of DNA material that is coded with “red” or “green” fluorescent dye.
The computer always makes the first move by activating the center well. Instead of using buttons or joysticks, a human player makes a “move” by adding a DNA sequence corresponding to their move in the eight remaining wells. The well chosen for the move by the human player responds by fluorescing green, indicating a match to the player’s DNA input. The move also triggers the computer to make a strategic counter-move in one of the remaining wells, which fluoresces red. The game play continues until the computer eventually wins, as it is pre-programmed to do, Macdonald says. Each move takes about 30 minutes, she says.