Optical interconnects have an important role to play in next-generation high-performance electronic systems by enabling power-efficient high-speed board-level communication links. Polymer-based optical waveguides is a leading technology for integrating optical links onto standard printed circuit boards as it is sufficiently low cost and enables cost-effective manufacturing and assembly. Various polymer-based optical backplanes have been reported in recent years enabling different on-board interconnection architectures. However, all currently demonstrated systems are purely passive, which limits therefore the reach, complexity and functionality of these on-board systems. Here, we present recent simulation and experimental studies towards the development of Er-doped polymer-based waveguide amplifiers. Two different approaches to integrate Er-doped materials in siloxane polymer are investigated: (i) ultrafast laser plasma implantation of Er-doped glasses and (ii) solution-based dispersion of Er-doped nanoparticles. Experimental and simulation results on the achievable performance from such waveguide amplifiers are presented focusing on impact of the waveguide loss and upconversion on the gain figure.