Phys.org April 24, 2023
Laguerre-Gaussian (LG) modes of light wave can carry the external torque of photons as they move through space. However, LG mode laser sources do not yet exist. An international team of researchers (China, USA – University of Arkansas) has experimentally demonstrated highly efficient, highly pure, broadly tunable, and topological-charge-controllable LG modes from a Janus optical parametric oscillator (OPO). They designed the Janus OPO featuring a two-faced cavity mode to guarantee an efficient evolution from a Gaussian-shaped fundamental pump mode to a desired LG parametric mode. The output LG mode had a tunable wavelength between 1.5 and 1.6 μm with a conversion efficiency >15 % , a controllable topological charge up to 4, and a mode purity as high as 97%, which provided a high-performance solid-state light source for high-end demands in multidimensional multiplexing/demultiplexing, control of spin-orbital coupling between light and atoms, and so on. According to the researchers their scheme can be further expanded to vector beam output and entangled LG photon generation, directions that will play important roles in areas such as atomic ensemble spin-orbit interaction, laser fabrication, and higher-entanglement quantum sources… read more. Open Access TECHNICAL ARTICLE
Diagram of Janus optical parametric oscillator. Credit: Advanced Photonics Nexus, Vol. 2, Issue 3, 036007 (April 2023)