The Raman laser is a byproduct of Raman scattering, discovered in 1928 by Nobel laureate Chandrasekhara Venkata Raman. It works as follows: light hits a substance, causing the atoms in the substance to vibrate sympathetically. The collision of photons with the substance causes some of the photons to gain or lose energy, resulting in a secondary light of a different wavelength. A Raman laser essentially involves taking this secondary light and then amplifying it by reflecting it and pumping energy into the system to emit a coherent laser beam.
In 2002, researchers at UCLA demonstrated Raman light emission from optical wires on a silicon chip and in 2004 they demonstrated the first silicon laser. In February 2005, researchers at Intel demonstrated the second generation of such lasers that are capable of operating in continuous-mode on silicon chips. It is expected that these breakthrough will greatly reduce the cost of optical computing and communications devices by 2010. Because of its crystalline structure, silicon atoms readily vibrate when hit with light. The Raman Effect, in fact, is 10,000 times stronger in silicon than standard glass.
The Raman effect can lead to higher energy photon emission, or, more usually, to lower energy photon emission.
* http://www.opticsexpress.org/abstract.cfm?URI=OPEX-12-21-5269, "Demonstration of a silicon Raman laser," by Ozdal Boyraz and Bahram Jalali. Also see http://www.sciam.com/article.cfm?chanID=sa006&colID=1&articleID=1365DED4-E7F2-99DF-3FD04062BB4186CC, "Making silicon laser," by Bahram Jalali
* http://www.nature.com/nature/journal/v433/n7027/full/nature03346.html, "A continuous-wave Raman silicon laser," by Haisheng Rong, Richard Jones, Ansheng Liu, Oded Cohen, Dani Hak, Alexander Fang and Mario Paniccia