This thesis describes the fabrication and characterizations of semiconductor nanomembranes, i.e., gallium arsenide (GaAs) photonic crystal (PC) and optomechanical nanomemebranes. Processing techniques are developed and optimized in order to fabricate PC membranes for quantum light sources and optomechanical nanomembranes for cavity cooling experiments. For PC cavities, several important processes have been extensively optimized such as the inductively coupled plasma (ICP) dry etch, the release of the membranes and the post-cleaning of the samples. GaAs optomechanical nanomembranes with a world-record mechanical Q-factor up to 1 million have been fabricated with two step selective wet etches. These optomechanical naonmembranes exhibit superb performances in cavity optomechanical cooling experiments in which a mechanical mode has been cooled from room temperature to 4 K. The interaction between single quantum dots (QDs) and PC cavities has been modeled in the framework of Jaynes-Cummings model (JCM) with the focus on single artificial atom lasers. In the experiments, a highly efficient single photon source with a collection efficiency up to 38% has been achieved and detailed measurements suggest that such a high efficiency could be attributed to the coupling to one of the higher-order cavity modes. Lasing oscillation has also been observed in the same systems. The comparison between the experimental lasing data to an advanced theory reveals that QDs lasing is fundamentally different from single atoms lasing due to the mesoscopic features of QDs. Random lasers in Anderson-localization regime have been achieved in PC waveguides where the laser output can be controlled with the underlying dispersion relation. The random lasers can be well fitted with a modified semiconductor laser rate equation, showing high-β factors and low mode volumes. The statistical measurements provide a complete and coherent picture of the mechanism and physical properties of a random laser in the Anderson-localization regime which paves the way to control and optimize random lasing in low dimensional optical nanostructures commonly used for tailoring the light-matter interaction.