CNS Enabled Technologies
CNS Seminar, Thursday, May 26th
LISE 303 12pm
"Dielectric Metasurfaces for the Visible Spectrum"
Robert Devlin, Capasso Group - Harvard SEAS
Abstract: Metasurfaces are optical elements that can mimic and go beyond the functionality of refractive optics, in a compact and planar configuration. Transmissive metasurfaces have been limited to infrared wavelengths because currently used materials have significant optical absorption and loss at visible wavelengths. We have recently demonstrated high performance dielectric metasurfaces using nanostructured titanium dioxide (TiO2). These TiO2 metasurfaces exhibit low surface roughness, highly anisotropic features and negligible optical loss at visible wavelengths. First, we will discuss the material properties, nanofabrication and optical performance of these metasurfaces. Next we will look at two examples of how we use these metasurfaces in our group to explore fundamental optical science and device applications. We show that we can use these metasurfaces to produce high fidelity optical vortex beams, which are promising for quantum communication, and can impart fractional and mixed orbital angular momentum on incident light with a single metasurface. We also demonstrate high numerical aperture meta-lenses showing diffraction limited focal spots and sub-wavelength resolution imaging at visible wavelengths.
About the Speaker: Robert Devlin completed his Bachelor of Science in Electrical Engineering and Master of Science in Materials Science and Engineering at Drexel University. While at Drexel he studied electronic transport in epitaxial, transition-metal-oxide films. He is currently pursuing his Ph.D. in Applied Physics at Harvard. His research in Professor Federico Capasso’s group focuses on engineering light-matter interactions through nanoscale patterning of materials. Specifically, he investigates material systems and nanofabrication techniques for creating planar optical elements, metasurfaces.
Advanced EELS and EFTEM Workshop, sponsored by Gatan
Tuesday May 24th, 10am-6pm, 11 Oxford St., LISE 303
This workshop combines presentations and extensive hands-on training on advanced EELS and EFTEM techniques and applications in the (S)TEM microscope. Practical experience with EELS is highly recommended. Participants will learn best practices to set up and optimize their EELS hardware and experimental protocols so they can capture and extract the maximum amount of compositional and chemical information from their TEM samples.
Click here to register.