Sandwich halves energy needed for photons

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A polymer has been improved to make it more useful for converting electricity into laser light.

Poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene], or MEH-PPV, can be integrated with silicon chips, and according to North Carolina State University, researchers have wanted to use the material for optical amplifiers and chemical sensors. But, the amount of energy needed to generate laser light from it had been so high it caused the MEH-PPV to degrade. However, the improvement has lowered the energy required for lasing by 50 per cent.

‘Think of a garden hose. If it has holes in it, water springs out through a million tiny leaks. But if you can eliminate those leaks, you confine the water in the hose and improve the water pressure. We’ve plugged the holes that were allowing light to leak out of the MEH-PPV,’ said Dr Lewis Reynolds. He is a teaching associate professor of materials science and engineering at NC State. He added: ‘This approach is fairly inexpensive and could also be easily scaled up for large-scale processing.’

The reduction in energy required to generate photons was also achieved by sandwiching the MEH-PPV between two materials that have matching indices of refraction, efficiently reflecting light back into the MEH-PPV and preventing light from escaping. The sandwich also limits MEH-PPV’s exposure to oxygen, reducing the photo-oxidation that occurs when materials are exposed to both light and oxygen.