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Laser Light Switch Could Leave Transistors in the Shade


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laser light switch experiment

This experimental set-up was used to show that it is possible to make a transistor that acts using laser light, not electric currents.

Credit: Martin Pototschnig / New Scientist

Researchers from the Swiss Federal Institute of Technology have developed an optical transistor that uses one laser beam to control another, potentially forming the foundation for a new generation of ultrafast light-based computers. The researchers say laser-based transistors can be used to create light-based computers, which would use optical fibers to carry light.

To create an optical transistor, the researchers suspended tetradecane, a hydrocarbon dye, in an organic liquid, which was then frozen using liquid helium to create a crystalline matrix in which individual dye molecules could be targeted using lasers. When a finely tuned orange laser beam is targeted on a dye molecule, most of the laser is absorbed, creating a much weaker output beam. However, when the molecule also is targeted with a green beam, the molecule starts producing a strong orange light of its own that boosts the power of the orange output beam. Switching the orange beam from weak to strong is similar to how a transistor's control electrode switches a current between on and off. The ability to make this switch using a single molecule could enable billions of optical transistors to be built on photonic chips.

From New Scientist
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