A wavelength multiplexed light source using multimode interference is
provided. The light source includes an input unit for inputting a
plurality of incident lights, input waveguides for individually guiding
the incident lights, a multimode waveguide having an input edge connected
to the input waveguides so that each incident light is coupled at a
predetermined position on an output edge opposite to the input edge and
an output waveguide connected to the predetermined position. Two incident
lights having adjacent wavelengths are arranged relative to a central
position of the input edge based on a respective wavelength for the
incident light.