[phas-dept] TAMUC Physics and Astronomy Colloquium This Thursday

[Bao-An Li]

Fall 2014 Colloquium
[cid:image001.jpg at 01CFF1C7.DB911CA0]
Nov. 20, Thursdays, 4-5pm in Science 127 (coffee and cookies served at 3:50pm)
All students currently enrolled in Physics 401 and 501 are required to attend all colloquia
Nonlinear optics of graphene and topological insulators
Prof. Alexey Belyanin, Texas A&M University

[r. Alexey Belyanin]Dr. Alexey Belyanin is Professor of Physics and Astronomy at Texas A&M University. He received his PhD in Physics in 1995 from the Russian Academy of Sciences, where he did research on high-energy astrophysics, cosmology, and quantum optics. His current research focuses on ultrafast, nonlinear, and quantum optics of semiconductors, nanostructures, and novel materials. He has coauthored over 110 articles in refereed journals and 5 patents.  Professor Belyanin has served as chair of international conferences and received a number of awards for research. His research was featured in news articles in Nature, Science, Nature Photonics, Laser Focus World, Optoelectronics Magazine, and other media. He is a Fellow of the American Physical Society. More information about Prof. Belyanin and his research can be found at http://people.physics.tamu.edu/belyanin/

Abstract:
Recently there has been a surge of interest in emergent 2D materials with chiral symmetry and gapless linear spectrum of free carriers near the Dirac point where the energy bands form a cone in the momentum space. Most notable examples include graphene and surface states in topological insulators such as Bi2Se3. So far the main effort was directed at studying their topological properties and carrier transport. In this talk we show that the systems with massless Dirac electrons possess a giant mid/far-infrared optical nonlinearity, perhaps the highest among known materials. Giant optical nonlinearity enables generation of coherent mid-infrared and terahertz radiation through resonant difference-frequency generation, four-wave mixing, and Raman scattering. Another interesting application is the generation of polarization-entangled light. Unique nonlinear properties of Dirac fermions enable schemes with a high signal to noise ratio and high generation rate of entangled photons. They also open an interesting possibility of detection and control of electron states near the Dirac point by means of nonlinear optics.
References:
[1] X. Yao and A. Belyanin, Phys. Rev. Lett. 108, 255503 (2012).
[2] M. Tokman, X. Yao and A. Belyanin, Phys. Rev. Lett. 110, 0774904 (2013).
[3] X. Yao, M. Tokman, and A. Belyanin, Phys. Rev. Lett. 112, 055501 (2014).


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