For quantum communication or optical computing, it is important to measure and to influence in which direction a light wave is oscillating. Now for the first time polarization control of a continuous laser wave (with a special glass fiber, which has mirrors attached at both ends) is possible.
The scientists are now able to enable the polarization control of a continuous light wave which is oscillating in one plane into a wave which oscillate in a circular way – which resembles the shape of a corkscrew. They achieve this effect by sending infrared laser light into a two-meter-long glass fiber made of silica. At both ends there are special mirrors, which 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 is trapped between these nearly perfect mirrors and starts to change its behavior: above a certain threshold of optical power the polarization control changes and the light polarization moves either clock- or anti-clockwise forward. The researchers could control the direction by changing the power of the light.