The progress in mid- and far- IR photonics has not mirrored the fast pace of visible-light optics because of inherent difficulties to produce bright IR light as well as to strongly mold and steer its path. However, in ionic crystals or heteropolar and polar-covalent semiconductors the oppositely-charged ions can "dance to the rhythm" of IR light at specific wavelength ranges. At these spectral ranges the aforementioned material support hybrid modes, known as phonon polaritons, that are part matter waves (phonons), part light waves. Although known since the 1950s their vast potential for IR beam control has been completely overlooked for decades. Just like in any other strong-coupling phenomenon, there exist a gap region between the phonon-polariton branches. Hence, within this spectrum, also known as the reststrahlen band, no EM modes may propagate and the material becomes almost 100% reflective. It is not surprising then why the huge potential of reststrahlen band material for strong IR light control was not recognized until recently.

In this talk, I will review the fundamentals of phonon-polariton material and discuss structural design routes to achieve new and extreme responses to IR light. I will then showcase related paradigm systems exhibiting behaviors of high interest to modern infrared photonics, such as polarization converters, frequency selective and near-perfect super-absorbers, as well as near-unidirectional thermal emitters.

Biography:

Stavroula Foteinopoulou is a Research Professor with the ECE Dept. of UNM. She received her Ph.D. in Condensed Matter Physics from Iowa State University and has held post-doctoral positions at the University of Namur in Belgium as well as the Institute of Electronic Structure and Laser of FORTH in Greece. Prior to joining the University of New Mexico, she was a Lecturer at the University of Exeter in UK. Her work in theoretical photonics focuses on conceiving new structured materials for extraordinary light control across the electromagnetic spectrum and has attracted to-date more than 3200 citations. Stavroula is the holder of one US patent, a senior member of both OSA and SPIE and the Chair of the annual SPIE conference Active Photonic Platforms for the last ten years. She also serves as an associate and feature editor for the OSA Journal of Optical Materials Express and as an associate editor for the Journal of the European Optical Society: Rapid Publications (JEOS-RP). In 2016 she was recognized by the American Physical Society (APS) as an outstanding referee, which is a lifetime award.