When boat paddles across a river and fighter jet flies through the sky, so it leaves wake all over in its path. Every time wakes occurs when something travels or go through a medium with speed faster than waves. In boat case its water waves and in case of jet, its shock waves, which also known as sonic booms.
Wake may occur, if there are waves, no matter those waves are water waves or light waves or sound waves. We all know and even researchers accept that in vacuum nothing can travel faster than the speed of light. In normal conditions, for few things it’s possible to move faster than the velocity of light in a material or medium to generate wake.
However; the best example is Cherenkov radiation, which produce wakes as electrical charges because liquid is faster than the phase velocity of light and it emits a glowing blue wake. Recently, a group of researchers from Harvard have created same wakes which seems to look like light waves while moving on the metallic surface that termed as “surface plasmons” and they stated that they can observe and control them.
For discovery credit goes to Vinton Hayes, Senior researcher from Electrical Engineering and Robert L. Wallace, Professor of Applied Physics at lab of Federico Capasso, which was published in the journal of Nature Nanotechnology.
According to Federico, the ability to control light is the power of technology and it will lead us to improve the technical efficiency of Google Glass, LEDs, holograms and many other technologies. Nano-optics is the future of nanotechnology and our research has ability to control the power of light at nano-scale.
Federico’s team developed a wave which can run faster than light with one dimensional meta-material. This meta-material have nano structure and after increasing the velocity of the water it can changes the phase of the surface plasmons. However; this nano structure act like the rudder of boat and it allows the wakes to be observed and control by the speed of water.
The team have also discovered the angle of incidence at which light shine on the meta-material whereas; there are also additional measure to control and use the polarized light which can reverse the direction of relative wake as per the velocity of running wave.
According to Daniel Wintz, who is lead author of the paper and researcher at Capasso lab, it’s important to not only observe the wakes, but also find multiple ways to steer and control them because getting an ability to control and manipulate light is not an easy task.
According to Antonio Ambrosio, who is co-lead author of paper and from SEAS and CNR (Italian Research Council), surface plasmons is not visible to eyes or cameras and due to that observation was challenging task. In order to observe the wake we can use experimental technique, which force plasmons from the surface with an aim to collect them through fiber optics and records the pictures.