Polarization Control For Optical Computing

It is critical to measure and influence the direction of oscillation of a light wave in quantum communication or optical computing. Polarization control of a continuous laser wave is possible for the first time (via a special glass fiber with mirrors attached at both ends).

Scientists can now control the polarization of a continuous light wave oscillating in one plane into a wave oscillating in a circular pattern resembling the shape of a corkscrew. They achieve this effect by directing infrared laser light into a two-meter-long silica glass fiber. Special mirrors at both ends reflect more than 99 percent of the light and are made of thin layers of tantalum pentoxide and silicon dioxide.

The light in the fiber becomes trapped between these nearly perfect mirrors and begins to change its behavior: above a certain threshold of optical power, the polarization control changes, and the light polarization moves forward either clockwise or anticlockwise. The researchers could control the direction by varying the brightness of the light.

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