When:
Thursday, October 20, 2016
4:00 PM - 5:30 PM CT
Where: Technological Institute, F160, 2145 Sheridan Road, Evanston, IL 60208 map it
Audience: Faculty/Staff - Student - Post Docs/Docs - Graduate Students
Contact:
Tina Hoff
Group: Physics and Astronomy Condensed Matter Physics Seminars
Category: Academic
Title: Learning to Live with Phonons: Mid- and Far-infrared Nanophotonics
Speaker: Anthony Hoffman, University of Notre Dame
Abstract: The importance of the mid-infrared for applications in sensing and imaging has grown rapidly due to the strong interaction of mid-infrared light with many molecules of interest and the development of optical materials and devices across this spectral region. Recent research has shown that development of the far-infrared could enable applications in astrophysics & astrochemistry, medicine, biology, homeland defense, and industry. Developing an optical toolkit—materials and sources—to extend this technological growth into the long-wavelength infrared is a significant and interesting challenge because the III-V semiconductors that enable extraordinary access to other portions of the electromagnetic (EM) spectrum exhibit significant optical loss at longer wavelengths. These losses arise from the coupling of EM radiation to free-carriers and phonons. While free-carrier loss can be controlled to an extent through the design and growth of semiconductor devices/materials, the loss due to phonons is intrinsic to the semiconductor lattice. In addition to optical absorption, phonons also limit the performance of quantum-well-based devices at these longer wavelengths due to rapid electron-phonon scattering. Here, I will present strategies for engineering materials and devices in the long-wavelength infrared, showing how we are learning to live with phonons.
This talk discusses our recent work towards engineering devices and materials that leverage optical phonons using bulk and surface phonon polariton modes. I will show how far-infrared absorption and emission can be controlled by using structured semiconductors. The talk will also discuss our efforts to circumvent of electron-phonon scattering by increasing the effective spontaneous emission rate of intersubband transitions through engineering light-matter coupling. I will show our recent work on extreme sub-diffraction hyperbolic metamaterial resonators and discuss their use for improving emission from intersubband devices.
Host: Jens Koch
Condensed Matter, Physics, Astronomy