Abstract: A combined multiplexer/demultiplexer for use in optical communication systems is disclosed. The combined multiplexer/demultiplexer includes a plurality of waveguide arrays and a plurality of signal carriers, each disposed substantially symmetrically about an optical axis of the device. In operation, a signal carrier emits a multiple wavelength optical signal that is received and directed to a dispersion apparatus by a light focusing device. The dispersion apparatus diffracts the optical signal into selected spectral components and reflects the spectral components back to the waveguide arrays through the light focusing device. The signal processing, such as multiplexing and demultiplexing, performed by each waveguide array depends on their configuration. The waveguide arrays may be configured to substantially simultaneously multiplex and/or demultiplex the spectral components.