We discuss fabrication of InGaAs quantum dot structures using the self-assembling growth technique with the Stranski-Krastanow growth mode in MOCVD, including optical ploperties of the nano-structures. The formation process of the quantum dot islands was clarified by observing the samples grown under various conditions with an atomic force microscope. A trial for self-alignment of the quantum dots was also investigated. On the basis of these results, as the first step toward the ultimate semiconductor lasers in which both electrons and photons are fully quantized, a vertical microcavity InGaAs/GaAs quantum dot laser was demonstrated. Finally a perspective of the quantum dot lasers is discussed, including the bottleneck issues and the impact of the quantum dot structures for reducing threshold current in wide bandgap lasers such as GaN lasers.