A scalable access network architecture is implemented experimentally to demonstrate gradual deployment of time- and wavelength-division-multiplexed passive optical networks (PONs) in a single-platform with minor changes in fiber infrastructure. This is achieved by the application of dynamic coarse-fine grooming to route multiple reflective optical network units of either time- or wavelength-multiplexed PONs collectively through coarse passbands of an arrayed waveguide grating (AWG). To evaluate experimentally the contribution of the excessive properties of wider-than-dense-passband AWGs to network performance, a readily available 2.7 nm device is utilized to substitute for 7 nm coarse-AWG prototypes. Experimental results have confirmed 10^−9 bidirectional transmission of data and continuous waves over 2.7-nm-wide passband windows of the AWG in the presence of 0.35 nm polarization-dependent wavelength shift and 1.5 dB polarization-dependent loss. In addition, Rayleigh backscattering is reported to be incapable of limiting the network performance.