We propose and demonstrate a new wavelength-division-multiplexed (WDM) passive optical network (PON) architecture that uses N x N waveguide grating routers in the remote node and central office for simultaneous multiplexing and demultiplexing of N - 1 channels in each direction. In the demonstrated network, a spectrum-sliced fiber amplifier light source was used to transmit 15 downstream channels operating at 500 Mb/s, The 155-Mb/s upstream channels used 1.5-mu m LED's, In addition, an erbium-doped fiber amplifier was used at the central office to compensate the slicing losses of low-power LED's, The crosstalk, caused by using WGR's for both multiplexing and demultiplexing channels, was suppressed to a negligible level by using two types of bandpass filters. There was no significant degradation in the receiver sensitivity caused by this crosstalk.