Analysis workforce develops multifunctional vortex beam for UV-visible spectra

The Fourth Industrial Revolution is driving exponential progress in knowledge transmission, and cost-effective, ultrafast, and compact optical communication applied sciences are urgently wanted to handle the exploding knowledge transmission quantity. Vortex beams, which exhibit a swirling form across the axis of propagation, have the potential to extend the quantity of knowledge that may be saved on the similar frequency.

As such, they signify a promising avenue for the event of high-capacity optical communication applied sciences that surpass 5G and pave the way in which for 6G. To that finish, a analysis workforce at Pohang College of Science and Expertise (POSTECH) has developed a vortex beam able to functioning with a variety of sunshine frequencies by way of the usage of a metasurface.

The findings are revealed within the journal Nano Letters.

Professor Junsuk Rho (Division of Mechanical Engineering, and Chemical Engineering), together with Ph.D. candidate Joohoon Kim (Division of Mechanical Engineering), led the workforce that proposed a metasurface able to independently controlling two orthogonal polarization states throughout the ultraviolet to seen gentle broadband wavelengths. As well as, the researchers demonstrated the flexibility to create and detect vortex beams with completely different topological costs utilizing the metasurface.

Orbital angular momentum (OAM) is a time period used to explain the swirling sample that gentle takes on because it travels. When gentle assumes this swirling sample, it’s known as a vortex beam. Vortex beams can retailer extra info on the similar frequency or polarization state than standard gentle beams can.

The impartial vortex beam of optical vortex beams has made them a vital instrument in optics with varied functions, together with optical tweezers and creating holographic movies. Nonetheless, creating optical vortex beams has historically required cumbersome and heavy tools known as spatial gentle modulators (SLMs). Moreover, introducing ultraviolet optical vortex beams has been difficult as a result of lack of SLMs that work on this vary.

Current advances in nanofabrication expertise have enabled the conclusion of high-efficiency, broadband, and multifunctional metasurfaces able to modulating many gentle properties, together with part, amplitude, and polarization. Nonetheless, regardless of these advances and ongoing analysis effort, controlling gentle within the ultraviolet vary stays a problem.

The analysis workforce opted for a skinny and light-weight metasurface to create a polarizer able to producing optical vortex beams when uncovered to ultraviolet gentle, versus the cumbersome and heavy SLMs historically used for this function. The researchers used silicon nitride, a fabric with a excessive refractive index and no absorption of ultraviolet gentle.

One of many limitations of metasurfaces is that their operate is completely fastened as soon as they’re processed, making them troublesome to switch. On this examine, nonetheless, the workforce broke the rotational symmetry of the metasurface to design it with completely different features relying on the polarization of the incoming gentle. This method permits for extra info to be saved on a single metasurface, opening up potential functions in varied fields.

Professor Rho defined, “Our analysis confirmed the multifunctionality of metasurfaces, which might create optical vortex beams with completely different topological costs based mostly on the polarization state of the incoming gentle. The creation of ultraviolet optical vortex beams additionally expands the potential functions of optical vortex beams.”