Spin-polarized light-emitting diodes and lasers are a promising technology for future high-speed optical communications with enhanced bandwidth and security. In such devices, circularly-polarized emission results from radiative recombination of spin-polarized carriers, which are injected from either a ferromagnetic metallic contact or magnetic semiconductor. Here we discuss the epitaxial growth and application of III-Mn-V diluted magnetic semiconductors and their nanostructures as injector layers in spin-polarized, surface-emitting diodes and lasers. A high polarization efficiency of 30% at 4.5 K is demonstrated in spin-LEDs having GaMnAs spin-injector layers and high-temperature operation (T < 180 K) is observed in spin-LEDs having a GaAs spin injector embedded with Mn-doped InAs quantum dot nano-magnets. Spin-polarized vertical cavity surface-emitting lasers having thin GaMnAs spin-injector layers have also been investigated.