Raman laser
Encyclopedia
The Raman laser is a byproduct of Raman scattering
, discovered in 1928 by Nobel laureate Chandrasekhara Venkata Raman
and Kariamanickam Srinivasa Krishnan
in liquids and independently by Grigory Landsberg
and Leonid Mandelshtam in crystals. When light hits a substance, it causes 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
takes this secondary light and amplifies it by reflecting it and pumping energy into the system to emit a coherent laser beam. The most significant difference between a Raman laser and a standard laser is the absence of population inversion
in a Raman laser.
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 breakthroughs 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 is 10,000 times stronger in silicon than in glass.
In 2007, researchers at JPL/Caltech have also discovered Raman lasing with fluorite resonators, demonstrating record low threshold and high efficiency.
The Raman effect can lead to higher energy photon
emission, or, more commonly, to lower energy photon emission.
Raman scattering
Raman scattering or the Raman effect is the inelastic scattering of a photon. It was discovered by Sir Chandrasekhara Venkata Raman and Kariamanickam Srinivasa Krishnan in liquids, and by Grigory Landsberg and Leonid Mandelstam in crystals....
, discovered in 1928 by Nobel laureate Chandrasekhara Venkata Raman
Chandrasekhara Venkata Raman
Sir Chandrasekhara Venkata Raman, FRS was an Indian physicist whose work was influential in the growth of science in the world. He was the recipient of the Nobel Prize for Physics in 1930 for the discovery that when light traverses a transparent material, some of the light that is deflected...
and Kariamanickam Srinivasa Krishnan
Kariamanickam Srinivasa Krishnan
Padma Bhushan Sir Kariamanickam Srinivasa Krishnan, FRS, was an Indian physicist. He was a co-discover of Raman scattering, for which his mentor C. V. Raman was awarded the 1930 Nobel Prize in Physics.-Early life:...
in liquids and independently by Grigory Landsberg
Grigory Landsberg
Grigory Samuilovich Landsberg was a Soviet physicist.Grigory S. Landsberg is a co-discoverer of inelastic combinatorial scattering of light used now in Raman spectroscopy. His major scientific contributions were in the fields of optics and spectroscopy....
and Leonid Mandelshtam in crystals. When light hits a substance, it causes 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
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
takes this secondary light and amplifies it by reflecting it and pumping energy into the system to emit a coherent laser beam. The most significant difference between a Raman laser and a standard laser is the absence of population inversion
Population inversion
In physics, specifically statistical mechanics, a population inversion occurs when a system exists in state with more members in an excited state than in lower energy states...
in a Raman laser.
Recent research
In 2002, researchers at UCLA demonstrated Raman light transmission from optical wires on a silicon quatum chip and in 2004 they demonstrated the first siliconSilicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
laser
Laser
A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...
. In February 2005, researchers at Intel demonstrated the second generation of such lasers that are capable of operating in continuous-mode on silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
chips. It is expected that these breakthroughs will greatly reduce the cost of optical computing and communications devices by 2010. Because of its crystalline structure, silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
atoms readily vibrate when hit with light. The Raman effect is 10,000 times stronger in silicon than in glass.
In 2007, researchers at JPL/Caltech have also discovered Raman lasing with fluorite resonators, demonstrating record low threshold and high efficiency.
The Raman effect can lead to higher energy photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
emission, or, more commonly, to lower energy photon emission.
External links
- Demonstration of a silicon Raman laser, by Ozdal Boyraz and Bahram Jalali.
- Making silicon lasers, by Bahram Jalali
- A continuous-wave Raman silicon laser, by Haisheng Rong, Richard Jones, Ansheng Liu, Oded Cohen, Dani Hak, Alexander Fang and Mario Paniccia
- Ultralow-threshold Raman lasing with CaF2 resonators, by Ivan Grudinin and Lute Maleki.