A laser for optical communications has been created

A laser for optical communications has been createdA laser for optical communications has been created. He will be able to encode information.

The new laser with a multilayer surface creates the world’s first super-chiral light. This is light with an ultrahigh angular momentum. It can be used as a type of “optical wrench” or for encoding information in optical communications.

Since light can carry angular momentum, this means that it can be transmitted to matter. The greater the momentum of the light carries, the more it can transmit. Instead of using a physical wrench to tighten things (for example, tightening the nuts), you can now light the nut on the nut and it will tighten itself.

The new laser generates a new “twisted light” of high purity, which was not previously observed from lasers, including the highest angular momentum reported by the device. At the same time, the researchers developed a nanostructured metasurface, which has the largest phase gradient ever created and allows working under high power conditions in a compact design. This is the first laser in the world to create exotic states of twisted structured light on demand.

This new laser is suitable for creating any desired chiral state of light with complete control of both light components of angular momentum (UM), spin (polarization), and orbital angular momentum (OMI) of light.

The laser design was made possible thanks to the full control offered by the new laser metasurface of nanometer size (1000 times smaller than the width of a human hair) developed by the Harvard Group. The metasurface consists of many tiny rods of nanomaterial that change light as they pass. Light passes through the surface many times, each time receiving a new turn. The result is the generation of new forms of chiral light that have not been observed in lasers to date, and complete control of the chirality of light in the source.

“What makes it special is that for light, the material has properties that cannot be found in nature, and therefore it is called metamaterial – a fictional material. There is currently a strong desire to control chiral matter with twisted light, and for this to work, you need light at a very high speed – super chiral light”.

Andrew Forbes, School of Physics at the University of Witwatersrand in Johannesburg, South Africa.

Various industries and research fields need super-chiral light to improve their processes, including in the food, computer, and biomedical industries. You can use this type of light for an optical drive when physical-mechanical systems will not work, for example, in microfluidic systems to control flow. Twisted light is used to propel micro-mechanisms, to propel flow, and simulate centrifuges with light.

Chirality is a term often used in chemistry to describe compounds that occur as mirror images of each other. These compounds have a “focus” and can be considered as right-handed or left-handed. For example, lemon and orange flavors are one and the same chemical compound, but differ only in their “length”. Light is also chiral but has two forms: spin (polarization) and orbital angular momentum. Spin is like planets orbiting around its axis, while the orbital angular momentum is like planets orbiting the Sun.

“Controlling the chirality of light in a source is challenging and very relevant because of the many applications that require it, from optical monitoring of chiral matter to metrology and communication. Full chiral control implies control of the total angular momentum, polarization, and orbital angular momentum”.

Andrew Forbes, School of Physics at the University of Witwatersrand in Johannesburg, South Africa.

Due to design constraints and implementation barriers, only a very small subset of chiral states has been obtained to date. The invented circuits were designed to control the helicity (a combination of rotation and linear motion) of the beams of the orbital angular momentum, but they also remain limited by this symmetrical set of modes. Until now, it was not possible to record any desired chiral state of light and obtain it with a laser.

The laser used a metasurface to fill the light with an ultrahigh angular momentum, giving it an unprecedented “rotation” in its phase, while controlling the polarization. By arbitrary control of the angular momentum, the standard spin-orbit symmetry can be broken so that the first laser provides complete control of the angular momentum of light in the source.

The metasurface was constructed from carefully created nanostructures to obtain the desired effect and is the most extreme (high-level and technological) structure of the orbital angular momentum that has been fabricated to date, with the highest of all recorded phase gradients. The nanometer resolution of the metasurface made it possible to create a high-quality vortex with low losses and a high damage threshold, which makes it possible to use a laser.

As a result, a laser was obtained that could affect the states of the orbital angular momentum of 10 and 100 simultaneously for the highest recorded angular momentum from the laser to date. In the special case, when the metasurface is configured to create symmetrical states, the laser then generates all the previous states of the orbital angular momentum, reported from non-standard structured light lasers.