Department of Physics

Shaping the Topology of Light on the Microscale

Structured light and structured matter are two fascinating branches of modern optics that recently started having a significant impact on each other. The synergy of complex beams, such as the beams carrying an orbital angular momentum (OAM), with nanostructured engineered media is likely to bring new dimensions to the science of light, ranging from fundamentally new regimes of spin-orbit interaction to novel ways of information encoding for the future optical communication systems. We will discuss fundamental optical phenomena at the interface of singular optics and engineered optical media and show that the unique optical properties of optical nanostructures open unlimited prospects to “engineer” light itself. For example, by exploiting the emerging non-Hermitian photonics design at an exceptional point, we demonstrate a microring laser generating a single-mode OAM vortex lasing with the ability to precisely define the topological charge of the OAM mode. We show that the polarization associated with OAM lasing can be further manipulated on demand, creating a radially polarized vortex emission. Next, by harnessing the properties of total momentum conservation, spin-orbit interaction, and optical non-Hermitian symmetry breaking, we demonstrate an OAM-tunable vortex microlaser, providing chiral light states of variable integer or fractional topological charges at a single telecommunication wavelength. These studies may provide a route for the development of the next generation of multidimensional OAM-spin-wavelength division multiplexing technology. Finally, we discuss our recent studies on tunable, robust topologically protected transport in photonic crystals at telecommunication wavelengths. We combine the properties of a planar silicon photonic crystal and the concept of topological protection to design, fabricate and characterize an optical topological insulator that exhibits the valley Hall effect. We show that the transmittances are the same for light propagation along a straight topological interface and one with four sharp turns. This result for the first time quantitatively demonstrated the suppression of backscattering due to the non-trivial topology of the structure.

 

 

About the Speaker

Natalia Litchinitser is a Professor of Electrical and Computer Engineering and a Professor of Physics at Duke University. Her research focuses on fundamental properties and applications structured light in engineered nanosctructures, metamaterials, topological photonics and nonlinear optics. Natalia M. Litchinitser earned her Ph.D. degree in Electrical Engineering from the Illinois Institute of Technology and a Master’s degree in Physics from Moscow State University in Russia. She completed her postdoctoral training at the Institute of Optics, University of Rochester in 2000. Natalia Litchinitser previously was a Professor of Electrical Engineering at the University at Buffalo, The State University of New York, a Member of Technical Staff at Bell Laboratories, Lucent Technologies and of a Senior Member of Technical Staff at Tyco Submarine Systems. She authored 7 invited book chapters and over 200 journal and conference research papers. She is a Fellow of the Optical Society of America, Fellow of the American Physical Society, and a Senior Member of the IEEE.