Coherent dynamics of exciton orbital angular momentum transferred by optical vortex pulses
| Autor: | Kyohhei Shigematsu, Ryuji Morita, Keisaku Yamane, Yasunori Toda |
|---|---|
| Rok vydání: | 2016 |
| Předmět: |
Physics
Angular momentum Condensed Matter::Other Exciton Dephasing Physics::Optics Nanotechnology 02 engineering and technology Condensed Matter::Mesoscopic Systems and Quantum Hall Effect 021001 nanoscience & nanotechnology 01 natural sciences Azimuthal quantum number Condensed Matter::Materials Science Total angular momentum quantum number Physics::Space Physics 0103 physical sciences Angular momentum of light Angular momentum coupling Orbital angular momentum of light Atomic physics 010306 general physics 0210 nano-technology |
| Zdroj: | Physical Review B. 93 |
| ISSN: | 2469-9969 2469-9950 |
| DOI: | 10.1103/physrevb.93.045205 |
| Popis: | 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 $(\ensuremath{\ell})$ 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 $\ensuremath{\ell}$ values under the same excitation conditions. The OAM decay times of the $\ensuremath{\ell}=1$ component are usually longer than those of the $\ensuremath{\ell}=0$ component. The $\ensuremath{\ell}\text{-dependent}$ OAM decay is supported by a phenomenological model which takes into account the local nonuniformity of the exciton dephasing. |
| Databáze: | OpenAIRE |
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