Metamaterials offer unprecedented control of the flow of light at nanoscale dimensions. However, three-dimensional (3D) metamaterials suffer from extreme optical losses, limiting their practical utility. Two-dimensional (2D) metasurfaces and, in particular, hyperbolic metasurfaces (HMSs) for propagating surface plasmon polaritons have been predicted to feature much lower loss while still exhibiting optical phenomena akin to those in 3D metamaterials. In this seminar, I will present our experimental realization of a visible-frequency HMS using single-crystalline silver nanostructures defined by lithographic and etching techniques. The resulting devices display the hallmark properties of metamaterials, such as negative refraction and diffraction-free propagation. Moreover, HMSs exhibit strong, dispersion-dependent spin-orbit coupling, enabling polarization- and wavelength-dependent routing of SPPs. Crucially, the low-loss, 2D nature of our devices results in a substantial, orders of magnitude improvement over 3D metamaterials in terms of optical loss. In an outlook, I will discuss how HMSs can be used for enhancing interactions of SPPs with quantum emitters — a new pathway for realizing solid-state single-photon nonlinear optical circuits.
Alex received a B.S. in Physics from the University of Pennsylvania in 2004 and a Ph.D. in Physics from the University of California, San Diego in 2012. He is currently a postdoctoral fellow in the group of Professor Hongkun Park at Harvard University. While at UCSD in the group of Professor Leonid Butov, he studied the low-temperature physics of indirect excitons in coupled quantum wells GaAs quantum wells while also developing excitonic optoelectronic devices. At Harvard, he is currently investigating pathways to couple solid-state optical emitters to high quality plasmonic systems as well as exploring the physics and optoelectronic possibilities of 2D monolayer optical materials.