This thesis describes the optical spectroscopic measurements of III-V nano-photonic circuit elements with integrated self-assembled quantum dot single-photon sources, as a step towards achieving an on-chip quantum optical circuit. An electrically controllable optical router consisting of an embedded quantum dot within a photonic crystal cavity which is selectively coupled to separate waveguides is presented. By tuning the voltage, the quantum dot emission can be directed into either waveguide. This is experimentally demonstrated with spatially resolved microphotoluminescence measurements. An electrically driven single-photon source monolithically integrated with nano-photonic circuitry is investigated. In this device, lectroluminescent emission from a single quantum dot is channelled through a suspended nanobeam waveguide. The emission is shown to be highly coherent with coherence properties which are sufficient to observe non-classical interference. Correlation and cross-correlation measurements are used to confirm the single-photon nature of the source and the propagation of the single photons. A detailed investigation of the on-chip two-photon interference of two dissimilar sources is presented. Photons emitted by a quantum dot embedded in one arm of a directional coupler are combined with photons originating from an external laser. The occurrence of Hong-Ou-Mandel interference is confirmed with cross-correlation measurements.