Abstract: An apparatus for demultiplexing a wavelength division multiplexed optical signal includes a plurality of wavelength channels each having a different signal wavelength. The apparatus includes a signal port and a plurality of grating modules. Each grating module has a coupler and a fiber Bragg grating which has a unique wavelength. The grating modules each have an input port, an optical tap, and an output port. The grating modules are configured in a row having a first end and a second end. This is accomplished by connecting the output port of each grating module to the input port of another grating module. The first end of the row of grating modules is connected to the signal port. The Bragg gratings reflect different signal wavelengths.