Self-assembled InAs/GaAs quantum dots ??QDs?? are studied by means of circular polarization-resolvedphotoluminescence and pump-probe differential reflectivity as a function of the excitation density using alinear polarized pump laser. We observe an unexpected large circular polarization anisotropy, which decreaseswith increasing excitation density for both experimental techniques. Comparison of the respective polarizationdegrees reveals a ratio of approximately 0.2. Moreover, the reflection measurements reveal circular dichroismwith a ratio of ??+ /??−=1.16. Circular dichroism in semiconductor QDs can be explained by the inducedmagnetism as a result of light confinement in QDs, providing an anisotropic coupling between the pumpinducedQD exciton and the circularly polarized probe field.
Bogaart, E. W., Haverkort, J. E. M., Mano, T., Lippen, van, T., Hamhuis, G. J., & Nötzel, R. (2006). Circular dichroism in InAs/GaAs quantum dots: confinement-induced magnetism. Physical Review B, 74(15), 153307-1/4. . https://doi.org/10.1103/PhysRevB.74.153307