An integrated DWDM receiver apparatus includes a support component and a silica-on-silicon substrate overlying the support component. The substrate includes a silica layer overlying a silicon layer and includes a first surface region and a second surface region. An optical demultiplexer is disposed within the silica layer under the first surface region and overlying the silicon layer. The optical demultiplexer includes a plurality of output waveguides and at least an input waveguide. The receiver apparatus includes one or more reflecting structures located in the silica layer under the second surface region. Each of the reflecting structures is optically coupled to a corresponding output waveguide. The receiver apparatus also includes one or more semiconductor photodetector array chips overlying the second surface region of the silica-on-silicon substrate. Each of the one or more photodetector array chips including one or more photodetectors which is optically coupled to a corresponding reflecting structure.