We report on the impurity-free vacancy-disordering effect in InAs/GaAs quantum-dot (QD) laser struc- ture based on seven dielectric capping layers. Compared to the typical SiO2 and Si3N4 films, HfO2 and SrTiO3 dielectric layers showed superior enhancement and suppression of intermixing up to 725°C, respectively. A QD peak ground-state differential blue shift of >175 nm (>148 meV) is obtained for HfO2 capped sample. Likewise, investigation of TiO2 ,A l2O3, and ZnO capping films showed unusual characteristics, such as intermixing-control caps at low annealing temperature (650°C) and interdiffusion-promoting caps at high temperatures (≥675°C). We qualitatively compared the degree of intermixing induced by these films by extracting the rate of intermixing and the temperature for ground-state and excited-state convergences. Based on our systematic characteriza- tion, we established reference intermixing processes based on seven different dielectric encapsulation materi- als. The tailored wavelength emission of ∼1060─1200 nm at room temperature and improved optical quality exhibited from intermixed QDs would serve as key materials for eventual realization of low-cost, compact, and agile lasers. Applications include solid-state laser pumping, optical communications, gas sensing, biomedi- cal imaging, green-yellow-orange coherent light generation, as well as addressing photonic integration via area- selective, and postgrowth bandgap engineering. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.