LMI Seminar: Semiconductor Dielectric Metasurfaces: Ultrafast Emission Control and Nonlinear Optics

Abstract:

Metamaterials and their 2D implementation – metasurfaces - have been used extensively for wavefront manipulation since their inception two decades ago. This has led to a revolution in optics due to the ability to design optical components with functionality and form factor that was unthinkable not long ago. Another use of metasurfaces relies on the ability to tailor distributions and intensities of local electromagnetic fields to study a variety of fundamental phenomena in light-matter interaction and create novel tunable and active devices.

Dielectric metasurfaces made from III-V semiconductors are particularly attractive for nonlinear optics, ultrafast and emission control applications. Lower dimensional emitters such as quantum dots can be embedded inside the metasurface resonators during epitaxial growth. I will show results of Purcell enhancement and recent results on beam steering of spontaneous emission on a subpicosecond timescale.

In the context of quantum and nonlinear optics, III-V semiconductors have among the highest optical nonlinearities but cannot be used in conventional phase-matched processes due to the symmetry of their nonlinear susceptibility tensor. However, as phase matching is relaxed when resonant nanoscale resonators are used, III-V semiconductor metasurfaces can be used for nonlinear processes in ways that have no equivalence when using macroscopic nonlinear media. Some of the results that I’ll present include harmonic generation, terahertz emission and generation of complex quantum states using spontaneous parametric down-conversion.