Wavelength-division multiplexers are photonic key components for the energy-efficient distribution of optical signals. In particular, microring filters in add/drop configuration and photonic switches are very suitable to perform the signal routing on integrated-optical circuits. In this work, wavelength selective filters and photonic networks are presented that were manufactured at low temperatures using low-loss hydrogenated amorphous silicon (a-Si:H). The advantages of using a high refractive index material as photonic layer are shown by the low device footprints, the low-power tune-ability, and the wide free spectral ranges supporting multiple parallel data channels and hence high optical bandwidth.