This disclosure relates to optical devices for quantum information processing applications. In one example implementation, a semiconductor structure is provided. The semiconductor structure may be embedded with single defects that can be individually addressed. An electric bias and/or one or more optical excitations may be configured to control the single defects in the semiconductor structure to produce single photons for use in quantum information processing. The electric bias and optical excitations are selected and adjusted to control various carrier processes and to reduce environmental charge instability of the single defects to achieve optical emission with wide wavelength tunability and narrow spectral linewidth. Electrically controlled single photon source and other electro-optical devices may be achieved.