Excitonic optical absorption in semiconductors under intense terahertz radiation
Zhang Tong-Yi (张同意), Zhao Wei (赵 卫)
State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, China
Abstract The excitonic optical absorption of GaAs bulk semiconductors under intense terahertz (THz) radiation is investigated numerically. The method of solving initial-value problems, combined with the perfect matched layer technique, is used to calculate the optical susceptibility. In the presence of a driving THz field, in addition to the usual exciton peaks, 2p replica of the dark 2p exciton and even-THz-photon-sidebands of the main exciton resonance emerge in the continuum above the band edge and below the main exciton resonance. Moreover, to understand the shift of the position of the main exciton peak under intense THz radiation, it is necessary to take into consideration both the dynamical Franz--Keldysh effect and ac Stark effect simultaneously. For moderate frequency fields, the main exciton peak decreases and broadens due to the field-induced ionization of the excitons with THz field increasing. However, for high frequency THz fields, the characteristics of the exciton recur even under very strong THz fields, which accords with the recent experimental results qualitatively.
Received: 16 April 2008
Revised: 16 June 2008
Accepted manuscript online:
PACS:
71.35.Cc
(Intrinsic properties of excitons; optical absorption spectra)
(Interactions of particles and radiation with matter)
Fund: Project supported by the National
Natural Science Foundation of China (Grant No 60777017), the
National Basic Research Program of China (Grant No 2007CB310405),
China Postdoctoral Scientists Foundation
(Grant No 20060390323), and K. C. Wong Education
Foundation, Hong Kong, China.
Cite this article:
Zhang Tong-Yi (张同意), Zhao Wei (赵 卫) Excitonic optical absorption in semiconductors under intense terahertz radiation 2008 Chin. Phys. B 17 4285
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