Excitonic optical absorption in semiconductors under intense terahertz radiation |
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Authors: | Zhang Tong-Yi and Zhao Wei |
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Institution: | State Key Laboratory of Transient Optics and Photonics, Xi'an
Institute of Optics and Precision Mechanics,
Chinese Academy of
Sciences, Xi'an 710119, China |
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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. |
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Keywords: | exciton optical absorption terahertz radiation dynamical Franz--Keldysh effect |
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