A
wavelength division
multiplexer integrating a dispersive element having a gradient
refractive index with optical lenses to provide efficient
coupling from a plurality of input optical fibers (each delivering a plurality of discrete wavelengths to the device) which are multiplexed to a single polychromatic beam for output to a single output
optical fiber. The device comprises: (a) an input means for accepting a plurality of optical input beams of different wavelengths from a plurality of optical sources, the means including a planar front surface onto which the optical beams are incident; (b) a dispersive element comprising a radial (or axial) gradient
refractive index for combining the plurality of optical input beams into a single
optical beam and operatively associated with the planar front surface; (c) a coupler subsystem secured to the dispersive element and comprising (1) a first homogeneous index boot lens having a planar front surface onto which the single
optical beam from the dispersive element is incident, (2) an axial gradient
refractive index collimating lens affixed to the first homogeneous index boot lens, and (3) a planar back surface from which the single
optical beam exits, operatively associated with the axial gradient refractive index collimating lens; and (d) an output means for outputting at least one multiplexed, polychromatic output beam to an optical
receiver, the means including the planar back surface. The device is fully bi-directional and may be operated in the forward direction as a
multiplexer and in the reverse direction as a
demultiplexer.