An international team of scientists from the Russian Quantum Center, MIPT, Lomonosov Moscow State University, and the University of Electronic Science and Technology of China has created a unique nanostructured surface that allows dynamic control of light polarization using heat. The discovery makes it possible not only to change the magnitude of the rotation of the plane of light polarization, but also its direction, which paves the way for the creation of tunable optical components, ultra-fast light modulators, and highly sensitive sensors of a new generation.
We have demonstrated that light can be controlled by another beam that heats the desired area. This is the basis for all-optical switches and modulators. In addition, such extreme temperature sensitivity makes our development an ideal platform for creating ultra-precise sensors capable of capturing thousandths of a degree.
Polarized electromagnetic waves have long been actively used in the operation of a large number of optical and optoelectronic devices, which are widely used in the creation of sensors, displays, and communication systems. Typically, materials with specially selected magneto-optical properties are used to obtain polarized radiation, the nature of which remains unchanged after their processing.
Researchers from the international scientific group have found that this problem can be circumvented with the help of the metasurface they created. This is how scientists call man-made structures made of many nanoparticles or other miniature elements that can interact with light or other waves in an unusual way. In this case, the researchers used nanoscale multilayering from a ferrite-ranto substrate, a magnetic material with unusual properties, and a set of many silicon "pillars" with a diameter of 280 nanometers applied to it.
Thus, silicon nanocylinders work as resonators, capturing light and repeatedly amplifying its interaction with the magnetic film. Thanks to this, even weak intrinsic magneto-optical effects of the film increase many times at certain resonant wavelengths, which allows very flexible manipulation of light polarization by heating the film to a temperature from 21 to 215 degrees Celsius.
We managed to "revive" the metasurface, making it controllable. Heating slightly changes the optical properties of materials, but due to the resonant nature of our structure, even these small changes lead to a giant shift in the magneto-optical response. We were able not only to dampen or amplify the effect, but to completely invert its sign, which was previously impossible to do in dynamic mode.