We present micro-photoluminescence measurements on single site-controlled InGaN/GaN quantum dots using two-photon excitation Furthermore, measurements of photoluminescence excitation and time-resolved photoluminescence are also presented. We show that two-photon excitation results in total suppression of the emission from the underlying quantum well, to which the quantum dots are couple, and yet strong quantum dot emission. We attribute this effect to the enhancement of the two-photon absorption in the quantum dots as a result of the zero-dimensional confinement compared to that of the quantum wells.
Jarjour, A. F., Taylor, R. A., Martin, R. W., & Watson, I. M. (2005). Two-photon absorption in site-controlled InGaN/GaN quantum dots. Physica Status Solidi C, 2(11), 3843-3846. https://doi.org/10.1002/pssc.200562028