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Coherent dynamics of exciton orbital angular momentum transferred by optical vortex pulses
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| Accessrights |
open access |
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©2016 American Physical Society
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| Description |
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Abstract
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The coherent dynamics of the exciton center-of-mass motion in bulk GaN are studied using degenerate four-wave-mixing (FWM) spectroscopy with Laguerre-Gaussian (LG) mode pulses. We evaluate the exciton orbital angular momentum (OAM) dynamics from the degree of OAM, which is derived from the distributions of OAM (topological charge) of the FWM signals. When excitons are excited with two single-mode LG pulses, the exciton OAM decay time significantly exceeds the exciton dephasing time, which can be attributed to high uniformity of the exciton dephasing in our bulk sample because the decoherence of the exciton OAM is governed by the angular variation in the exciton dephasing. We also analyze the topological charge (ℓ) dependence of the OAM decay using a multiple-mode LG pump pulse, which allows us to simultaneously observe the dynamics of the exciton OAM for different ℓ values under the same excitation conditions. The OAM decay times of the ℓ=1 component are usually longer than those of the ℓ=0 component. The ℓ-dependent OAM decay is supported by a phenomenological model which takes into account the local nonuniformity of the exciton dephasing.
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American Physical Society
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| Resource Type |
journal article |
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VoR |
| Identifier |
HDL
http://hdl.handle.net/2115/60593
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DOI
https://doi.org/10.1103/PhysRevB.93.045205
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| Journal |
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PISSN
2469-9950
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EISSN
2469-9969
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Physical Review B
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Volume Number93
Issue Number4
Page Start045205-1
Page End045205-8
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| Oaidate |
2023-07-26 |
