The use of polymer waveguides for the design and fabrication of devices for wavelength division multiplexing (WDM) at 1550 nm is described. Single mode 1 X 2, 1 X 4 and 1 X 8 splitters and combiners have been fabricated using photosensitive polyimide materials on silicon substrates. Good division of light was achieved in the devices, and waveguide facets could be cleaved to allow efficient coupling from optical fibers. The design of phased array wavelength demultiplexers for polymer waveguide technologies is described and compared to competitive technologies. Optimization of the trade-off between device size and waveguide cross-section is discussed and preliminary device designs for different polymer systems are presented.