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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


Physical Sciences and Mathematics

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This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in T. Piwonski et al., Appl. Phys. Lett. 97, 051107 (2010) and may be found at

The authors would like to gratefully acknowledge discussions with R. J. Manning. This study has been supported by Science Foundation Ireland under Contract No. SFI 07/IN.1/I929, the INSPIRE Programme, funded by the Irish Government’s Programme for Research in Third Level Institutions, Cycle 4, National Development Plan 2007–2013, and the Institute of Technology Ireland’s Strand I Programme and the Tyndall National Access Program.


The refractive index dynamics of InAs/GaAs quantum dot based waveguide absorbers is studied using heterodyne pump-probe measurements. Absorption reduction due to the pump can be accompanied by either positive or negative refractive index changes depending on the wavelength used. This change in sign of the phase amplitude coupling can be understood by considering the atomlike nature of the quantum dot transitions involved.