Phys.org August 8, 2023 Orbital angular momentum (OAM) spectrum diagnosis is a fundamental building block for diverse OAM-based systems. Among others, the simple on-axis interferometric measurement can retrieve the amplitude and phase information of complex OAM spectra in a few shots. Yet, its single-shot retrieval remains elusive, due to the signal–signal beat interference inherent in the measurement. Researchers in Switzerland have introduced the concept of Kramers–Kronig (KK) receiver in coherent communications to the OAM domain, enabling rigorous, single-shot OAM spectrum measurement. They explained in detail the working principle and the requirement of the KK method and applied the technique to […]
Tag Archives: Structured light
Topologically structured light detects the position of nano-objects with atomic resolution
Phys.org May 19, 2023 Despite recent progress in optical imaging and metrology there remains a substantial resolution gap between atomic-scale transmission electron microscopy and optical techniques. An international team of researchers (UK, Singapore) demonstrated atomic scale metrology by collecting single-shot images of the diffraction pattern of topologically structured light scattered on a suspended nanowire to determine its position relative to the fixed edges of the sample. They trained a deep learning algorithm that could predict the positions of a given nanowire based on the scattered light pattern recorded by the team’s sensor. If a sub-wavelength object moves in such a […]
Researchers use structured light on a chip in another photonics breakthrough
Phys.org May 17, 2023 Despite recent demonstrations of various topological photonic phases, the full potential offered by Dirac photonic systems, specifically their ability to emulate the spin degree of freedom—referred to as pseudo-spin—beyond topological boundary modes has remained underexplored. An international team of researcher (USA – City College of New York, AFRL (Eglin AFB), Australia) showed an example of relativistic-like trapping in photonic system that realizes Dirac-like dispersion with spatially inhomogeneous mass term. The modes trapped by such cavities, their energy levels, and corresponding orbitals were characterized through optical imaging in real and momentum space. The fabricated cavities hosted a […]
Photonic hopfions: Light shaped as a smoke ring that behaves like a particle
Phys.org January 19, 2023 Achieving hopfions with light waves is very elusive. An international team of researchers (UK, China) proposed and demonstrated photonic counterparts of hopfions with exact characteristics of Hopf vibration, Hopf index, and Hopf mapping from real-space vector beams to homotopic hyperspheres representing polarization states. They experimentally generated photonic hopfions with on-demand high-order Hopf indices and independently controlled topological textures, including Néel-, Bloch-, and antiskyrmionic types. They also demonstrated a robust free-space transport of photonic hopfions, thus showing the potential of hopfions for developing optical topological informatics and communications. According to the researchers their work provides a theoretical […]
Direct generation of complex structured light
Phys.org March 18, 2022 An international team of researchers (China, USA – Arizona State University) generated structured transverse mode locking (TML) beams and second harmonic generation (SHG) beams by a sandwich-like microchip laser cavity that was passively Q-switched. They observed many rare SHG far-field beam patterns and their experiments showed good agreement with the simulations. It showed that parametric variation for the TML modes greatly changes the far-field beam patterns of the SHG beam. Generated SHG beam patterns vary with the propagation, and then they remain stable into the far field. The SHG beam patterns were observed to have more […]
Structured light promises path to faster, more secure communications
Eurekalert November 5, 2019 Researchers in South Africa review the progress being made in using structured light in quantum protocols to create a larger encoding alphabet, stronger security and better resistance to noise. Since patterns of light can be distinguished from each other, they can be used as a form of alphabet. Its information capacity is much higher than polarized light and security is stronger, and the robustness to noise is improved. It turns out that many protocols can be efficiently implemented withotterns of light. Unfortunately, the toolkit to manage these patterns is still underdeveloped and requires a lot of […]