Recent progress in analyzing AlGaAs-GaAs semiconductor heterointerfaces using optical methods, such as photoluminescent spectroscopy, photo-absorption spectroscopy, photoluminescence-excitation spectroscopy and laser-Raman spectroscopy, is reviewed. Three types of interface disorders are discussed : compositional grading parallel to the growth direction, alloy clustering, and island-like structure formation on the interface (interface roughness). When AlAs-GaAs stacked layers are thin enough to form quantum wells or a superlattice, these interface disorders manifest themselves in the optical spectrum, that is, in a broadening of the line width, and a peak shift and additional sub-peaks or shoulders.These optical methods are sufficiently sensitive that differences in the thickness of the grading of a few Angstrom, the existence of alloy clusters of a few atomic diameter, and differences of the height of interface roughness of one monolayer can be detected. Emphasis is put on the potential of laser-Raman and picosecond time-resolved spectroscopy to investigate the unique properties of superlattice stuctures.