New, Efficient Polariton Laser-Like Device CreatedCategory: Science & Technology
Posted: June 10, 2014 04:23PM
Something that has become all but lost in modern culture is that 'laser' was not originally a word, but an acronym. It stands for Light Amplification by Stimulated Emission of Radiation, which actually does a good job of explaining how they work. However researchers at the University of Michigan have developed a new light-source that creates a laser-like beam by a different means, allowing it to be much more efficient.
Lasers work by pumping energy into electrons, causing them to leap from their low-energy ground state, to a higher energy state. As the higher state is not stable, the electrons will eventually fall back to the ground state, releasing the energy difference as a photon of a specific wavelength. What the Michigan researchers built though is a polariton laser that operates in a significantly different way. Polaritons are the combination of photons and excitons, which are themselves the combination of an electron and the positively charged hole they leave in a material. Typically a polariton will breakdown quickly, but by feeding them just the right amount of energy, the polaritons will bounce around and enter what the researchers call a coherent pool. When they then decay, the photons released are all the same frequency. Due to the polaritons not relying on the electrons entering a high energy state, the polariton laser requires 250 times less power than comparable lasers. The reason it is technically a laser is because of instead of operating with the stimulated emission of radiation, it works from the stimulated scattering of the polaritons.
Polariton lasers have been built before, but this design differs greatly as it is able to operate at room temperature. That combined with the low power requirement could allow them to be integrated into computer chips and enable wires to be replaced with optics inside and between our computers.
Source: University of Michigan