invention the system 10 is adapted to combining broadband and baseband signals the baseband signals modulate addressable gain sections of a waveguide grating router laser wgrl and broadband signals modulate a shared gain section of the wgrl so as to combine the broadband signals with each modulated baseband channel a waveguide grating router demultiplexes the received channels and a receiver circuit splits the baseband and broadband signals in this manner system 10 can simultaneously transmit n wdm channels each channel modulated with a broadband signal generally fig1 illustrates a waveguide grating router laser 20 a data generator or like baseband signal source 30 a broadband signal source 40 a waveguide or light transmission medium 50 a waveguide grating router 90 and receiver circuits 60 the wgrl 20 includes separately addressable gain sections 21 1 21 2 21 3 21 n where n is equal to the number of baseband signals received from source 30 each addressable gain section 21 1 21 2 21 3 21 n is coupled to waveguide grating router 22 which is a routing device operating as a multiplexer demultiplexer of optical frequencies the output at 22 39 of wgr 22 is coupled to a shared gain section 23 a baseband signal source 30 such as a data generator produces baseband signals filtered by low pass filters 31 1 31 2 31 3 31 n the baseband signals received from source 30 and lowpass filtered at filters 31.