This chapter introduces the background for the development of highly functional photonic devices as building blocks in the modern optical networks. Advantages and precautions of adopting polymer materials for various photonic applications are discussed. After a short overview of some typical fabrication processes related to polymer optical materials, the chapter continues to explore the performance of various passive photonic components, including conventional arrayed waveguide gratings and multimode interference devices, but also novel elements such as fiber attachment grooves, thin film elements, and dielectric waveguides in polymer. As a response to the current market need for low-cost and highly efficient tunable devices, three types of thermally tunable components are introduced. To add light sources and detectors to the optical circuit, InP-based active components are integrated on the polymer motherboard, either by butt-joint coupling or vertical surface coupling via a 45° mirror. The concept of hybrid integration is thus presented. To be deployed in the optical networks in a plug-and-play manner, the optical devices must be assembled and placed nicely into a package, with proper electrical and optical contacts. The procedure to build up optical assemblies and modules is briefly covered. In the end, the device reliability issues are discussed and various tests according to the industry standards are shown.
