Scientists fund new use for the trusty funnel - concentrating light!
We all know how useful funnels can be for decanting some leftover soup into a container, but now a team of international scientists has shown that the funnel is also handy for efficiently concentrating light. However, you won't find the funnels used by the scientists in a kitchen, as to concentrate light they need to be around 10,000 times smaller than the funnels we are familiar with. Writing in the journal Nature Photonics, the researchers, from Germany, South Korea and the United States, explain how they managed to concentrate the energy of infrared light pulses with a nano funnel and use the concentrated energy to generate extreme ultraviolet (EUV) light flashes. These flashes, which repeated 75 million times per second, lasted only a few femtoseconds - the unit of time equal to one millionth of one billionth of a second. Light is convertible and the wavelengths composing the light can change through interactions with matter, where both the type and shape of the material are important for the frequency conversion. The team was able to modify light waves with a nano funnel made out of silver. The scientists converted femtosecond laser pulses in the infrared spectral range to femtosecond light flashes in the EUV. Ultrashort, pulsed EUV light is used in laser physics to explore the inside of atoms and molecules, therefore technological knowledge like this will soon enable scientists to measure the movement of electrons with the highest spatial and temporal resolution. The core of the experiment was a small, only a few micrometres long, slightly elliptical funnel made out of silver and filled with xenon (Xe) gas. The infrared light pulses were sent into the funnel entrance where they travel through towards the small exit. The electromagnetic forces of the light result in density fluctuations of the electrons on the inside of the funnel. Here, a small patch of the metal surface was positively charged, the next one negative and so on, resulting in new electromagnetic fields on the inside of the funnel, which are called surface plasmon polaritons. The surface plasmon polaritons travel towards the tip of the funnel where its conical shape results in a concentration of their fields. One of the study authors, Professor Mark Stockman from Georgia State University in the United States, comments: 'The field on the inside of the funnel can become a few hundred times stronger than the field of the incident infrared light. This enhanced field results in the generation of EUV light in the Xe gas.'For more information, please visit:Max Planck Institute of Quantum Optics:http://www.mpq.mpg.de/cms/mpq/en/index.html
Countries
Germany, South Korea, United States