The quest to find new methods to slow down or even stop light waves has been a longstanding goal in the field of photonics. It is believed that achieving this feat could lead to significant advancements in various photonic devices, including lasers, LED displays, fiber-optics, and sensors. Recently, a group of scientists from AMOLF and Delft University of Technology in the Netherlands have unveiled a groundbreaking technique that involves trapping light waves using a specially engineered silicon crystal. This method offers a fresh and flexible approach to making light waves stand completely still, opening up a realm of possibilities for future technological applications.
The foundation of this innovative approach lies in the manipulation of electrons using two-dimensional materials like graphene. Typically, electrons in a conducting material have the freedom to move unimpeded, akin to zooming along a highway. However, by applying a magnetic field, the movement of electrons can be confined to specific energies known as Landau levels. Interestingly, the researchers discovered that two-dimensional materials such as graphene can also induce this phenomenon. By distorting the graphene structure, for example, through stretching, the electrons can be locked into Landau levels, transforming the conductive material into an insulator. Building on this concept, the scientists sought to identify a material that could exhibit a similar influence on photons as distorted graphene has on electrons.
The team’s exploration led them to experiment with a material known as a photonic crystal, which bears resemblances to graphene in its ability to manipulate light. Typically consisting of a two-dimensional array of holes in a silicon layer, a photonic crystal allows light to move freely within it, similar to electrons in graphene. By strategically altering the regular pattern of the holes in the crystal, the researchers were able to deform the array and immobilize the photons. This innovative approach essentially created Landau levels for photons, mimicking the effect achieved with electrons in graphene. The team’s honeycombed photonic crystals demonstrated the capacity to confine light by inducing various forms of deformation, such as curving or warping. Furthermore, the researchers were able to introduce different types of warping in distinct areas of the material, resulting in a photonic crystal where light flows freely in some sections while becoming trapped in others.
While this discovery represents a significant leap forward in the manipulation of light at nanoscale levels, further development is required to harness its full potential. The ability to control and confine light in such a precise manner paves the way for on-chip applications that could revolutionize the field of photonics. By confining light on a nanoscale and halting its movement, the strength of the light can be vastly enhanced. This breakthrough not only holds promise for enhancing the performance of existing photonic devices but also for enabling the development of entirely new technologies that rely on the precise control of light. As physicist Ewold Verhagen aptly puts it, “This principle offers a new approach to slow down light fields and thereby enhance their strength. Realizing this on a chip is particularly important for many applications.” In essence, the ability to stall light waves opens up a world of possibilities for the future of photonic devices.
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