Scientists have actually demonstrated how to control light at nanoscale using photonic crystals, simulating the effects of electromagnetic fields on electrons. This development in photon manipulation can significantly impact the development of nanophotonic chips, enhancing devices like lasers and quantum light sources. (Artists idea.) Credit: SciTechDaily.comAMOLF scientists, in collaboration with Delft University of Technology, was successful in bringing light waves to a stop by warping the two-dimensional photonic crystal that includes them. The researchers revealed that even a subtle contortion can have a considerable impact on photons in the crystal. This resembles the result that a magnetic field has on electrons.” This principle provides a new method to decrease light fields and therefore improve their strength. Understanding this on a chip is particularly essential for numerous applications,” states AMOLF-group leader Ewold Verhagen. The researchers released their findings in the scientific journal Nature Photonics on April 23rd. Concurrently, a research study team from Pennsylvania State University published an article in this journal about how they showed– individually from the Dutch group– a similar result. Manipulating the circulation of light in a product at little scales is helpful for the advancement of nanophotonic chips. For electrons such control can be realized using electromagnetic fields; the Lorentz force steers the movement of electrons. This is difficult for photons since they do not have charge. Researchers in the Photonic Forces group at AMOLF are searching for techniques and materials that would allow them to use forces to photons that look like the impacts of magnetic fields.Electrons” We searched for inspiration at the way in which electrons act in materials. In a conductor, electrons can in principle move easily, but an external electromagnetic field can stop this. If they have very specific energies, the circular movement caused by the magnetic field stops conduction and as such electrons can just exist in the product. These energy levels are called Landau levels, and they are characteristic for electrons in a magnetic field,” says Verhagen.” But, in the two-dimensional material graphene– that includes a single layer of carbon atoms organized in a crystal– these Landau levels can likewise be triggered by a different mechanism than an electromagnetic field. In general, graphene is a good electronic conductor, but this modifications when the crystal array is deformed, for circumstances by extending it like elastics. Such mechanical deformation stops conduction; the material develops into an insulator and consequently, the electrons are bound to Landau levels. The contortion of graphene has a comparable result on electrons in a material as a magnetic field, even without a magnet. If a comparable technique would likewise work for photons, we asked ourselves.” Electron microscopy picture of a photonic crystal. The diameter of the triangular holes is 300 nanometer. The curvature of the crystal selection stops the light waves in the crystal from moving. Credit: AMOLFPhotonic CrystalIn a collaboration with Kobus Kuipers of Delft University of Technology, the group of Verhagen indeed demonstrated a comparable effect for light in a photonic crystal. “A photonic crystal normally includes a routine– 2 dimensional– pattern of holes in a silicon layer. Light can move freely in this material, similar to electrons in graphene,” states first author René Barczyk who successfully protected his PhD thesis on this topic in 2015. “Breaking this consistency in exactly the best way will warp the variety and subsequently lock the photons. This is how we create Landau levels for photons.” In Landau levels light waves no longer move; they do not stream through the crystal but stall. The scientists was successful in showing this, showing that the contortion of the crystal range has a comparable effect on photons as an electromagnetic field on electrons.Verhagen specified, “By playing with the deformation pattern, we even handled to develop different types of reliable magnetic fields in one material. As an outcome, photons can move through certain parts of the product but not in others. These insights also supply new methods to steer light on a chip.” Simultaneous ExperimentsThe work of Verhagen and his group was inspired by theoretical predictions of researchers at Pennsylvania State University and Columbia University.Verhagen recalls: “When we were doing our very first measurements, I occurred to talk to among the authors of this other study. When it ended up that they were likewise looking for speculative evidence of the impact, we chose not to compete in being very first to publish but instead to send the work at the same time to the publisher. While some information in the approach differed, both teams were able to stop light waves from moving and observe Landau levels by warping a two-dimensional photonic crystal.” This brings on-chip applications closer,” states Verhagen. “If we can restrict light at the nanoscale and bring it to a halt like this, its strength will be enhanced greatly. And not just at one area, but over the entire crystal surface. Such light concentration is extremely essential in nanophotonic devices, for example for the development of effective lasers or quantum light sources.” Reference: “Observation of Landau levels and chiral edge states in photonic crystals through pseudomagnetic fields caused by artificial stress” by René Barczyk, L. Kuipers and Ewold Verhagen, 23 April 2024, Nature Photonics.DOI: 10.1038/ s41566-024-01412-3.
Scientists have actually demonstrated how to manipulate light at nanoscale using photonic crystals, mimicing the impacts of magnetic fields on electrons. The curvature of the crystal range stops the light waves in the crystal from moving. Credit: AMOLFPhotonic CrystalIn a cooperation with Kobus Kuipers of Delft University of Technology, the group of Verhagen certainly demonstrated a comparable result for light in a photonic crystal.” In Landau levels light waves no longer move; they do not flow through the crystal however stand still. While some information in the approach varied, both groups were able to stop light waves from moving and observe Landau levels by deforming a two-dimensional photonic crystal.