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Abstract: |
This talk gives an overview of the application of terahertz
(THz) spectroscopy to explore novel aspects of the many-particle
excitations in condensed matter systems. After a brief
introduction of the main concepts, a series of recent
experiments and their theoretical analysis will be discussed.
Background: In the last few years, the
interaction of terahertz (THz) radiation with semiconductors,
metals, graphene, or other materials has attracted significant
attention worldwide. After our original suggestion to used THz
radiation to identify excitonic populations in semiconductors
[1], our group developed a microscopic description allowing us
to explain a large variety of experiments [2-5]. Examples
include excitonic population effects in laser excited
semiconductors [6,7], the generation of THz gain via
non-resonant optical pumping [8], the ultrafast response of
semiconductors to single-cycle THz pulses [9], as well as the
coherent THz control of optically dark excitonic populations
[10]. The interaction of electron plasmas with THz radiation has
been studied [11,12] and the detection of THz radiation with
diode lasers has been analyzed [13]. Recent work includes the
study of Fano signatures in the intersubband THz response of
optically excited quantum wells [14], the THz-detection of
plasmonic resonances in quantum wells and high-mobility
transistor structures, the THz response of grapheme, as well as
extreme nonlinear optical effects of semiconductors and metals
under intense THz irradiation.
[1] M. Kira, W.
Hoyer, T. Stroucken, and S.W. Koch, ``Exciton Formation in
Semiconductors and Influence of Photonic Environment'', Phys.
Rev. Lett. 87,
176401 (2001)
[2] S.W. Koch, M.
Kira, G. Khitrova, and H.M. Gibbs, ``Semiconductor Excitons in
New Light'',
Nature Materials 5,
523 - 532 (2006)
[3] M. Kira and
S.W. Koch, ''Many-Body Correlations and Excitonic Effects in
Semiconductor Spectroscopy'', invited review article, Prog.
Quant. Electron. 30,
155-296 (2006)
[4] M. Kira, W.
Hoyer, and S.W. Koch, ``Microscopic Theory of the Semiconductor
Terahertz Response'', phys. stat. sol.
b238, 443-450 (2003)
[5] M. Kira and
S.W. Koch, ``Microscopic Theory of Optical Excitations,
Photoluminescence, and Terahertz Response in Semiconductors'',
invited article in special issue on "Correlated Matter in
Radiation Fields: From Femtosecond Spectroscopy to the Free
Electron Laser", Europ. Phys. Journ.
D 36, 143 (2005)
[6] J.T. Steiner,
M. Kira, S.W. Koch, T. Grunwald, D. Köhler, S. Chatterjee, G.
Khitrova, and H.M. Gibbs, ``Interaction of THz Radiation with
Semiconductors: Microscopic Theory and Experiments'', Adv. in
Solid State Phys. (Festk.probl.) 2007 |