(EN) The present invention provides an apparatus and method for high-density optical wavelength division multiplexing (WDM) using a single optical source. An optical wavelength division multiplexer in accordance with the present invention includes an optical source providing an optical pulse signal. A wavelength splitter separates the optical pulse signal spectrum into a plurality of channel signals at different wavelengths such that each channel signal may be separately modulated or otherwise processed. A wavelength combiner then recombines the separately modulated channel signals to provide a high-density WDM optical signal particularly well-suited for use in optical circuit interconnection and optical communication network applications. The high-density single-source multiplexer of the present invention may also be conveniently adjusted to align channel signal wavelengths or to compensate for optical fiber dispersion.