For the first time, a team of researchers at North Carolina State University developed a technique to control the velocity of the photon using the Electric field. This breakthrough project will help to shape a light into arbitrary patterns. So, this could be helpful to find applications in goggle-free virtual reality lenses and projectors.
According to NC State university's Assistant Prof. Linyou Cao, this development follows similar technique which is used for computation logic in the computer. In a computer, the electric field is used to turn electric current on or off, which corresponds to logic 1 and logic 0, the basis of binary code.
Similarly, in this technique electric field may be controlled the light like strong or weak, spread or focused, pointing one direction or others. Prof. Linyou told that the binary code has changed the way of computation and this new technique will likely change the way of observation.
However, guiding the visible light by an electric field is a very difficult task as the light source is nothing but the stream of photons. A photon is a massless elementary particle with no electric charge and is a stable particle. Principally, Electric field related with the charged particle and that's why a photon is characteristically irresponsible to electric fields.
In this project, researcher finds a distinct way of light control where they used an electric field to control the refractive index of the material instead of the photon. Refractive index actually describes that how light propagates through a medium. More clearly refractive index offers to determine the way materials reflect, transmit, scatter and absorb the light. So, it is a key factor to control a light by using an electric field, The more one can control a material's refractive index, the more he can control over light.
Though, it's practically very difficult to tune refractive index with electric fields, says Prof. Cao. Until this latest technique, researchers were able to change the index for visible light by between 0.1 and 1 percent. To improve the previous performance researcher are used a class of atomically thin semiconductor materials called Transition-Metal Dichalcogenide Monolayers.
A detailed report about the latest project, researchers have published a paper in Nano Letters on May 15. As the test subject, they used thin films of molybdenum sulfide, tungsten sulfide, and tungsten selenide. According to a report, this new technique could able to tune the refractive index by 60 percent.
To change the refractive index they used a technique by applying a charge to two-dimensional semiconductor materials, said Prof. Cao. He also added that the technique is very similar that can use to charge the transistors in a computer chip. Using this technique, they achieved significant, tunable changes in the refractive index within the red range of the visible spectrum. The degree of change of the refractive index is directly proportional to the applied charged.
Lead author Yiling Yu said This technique may provide capabilities to control the amplitude and phase of the light pixel by pixel in a way as fast as modern computers. Now they are optimizing the technique to achieve even larger changes in the refractive index. At the same time, they have a plan to find whether the technique is decent for other wavelengths.
