Waveguide grating router having a predetermined composite amplitude spectrum

In a waveguide grating router, a predetermined composite transmission spectrum output is achieved by eliminating loss imbalances through the use of variable loss elements (320). The variable loss elements are introduced to the waveguide grating router's waveguide ports (310), such that the loss of a transmitted signal is independent of wavelength. The waveguide grating router includes at least one input waveguide (302) and a plurality of output waveguides. The variable loss element is introduced to a predetermined group of output waveguides to produce a predetermined composite amplitude spectrum of the output signals. To provide a predetermined composite amplitude output spectrum, the variable loss elements may be implemented in a variety of ways, including a method of electrically controlling the router's waveguide ports to introduce more loss.