We report recent activities and achievements on the development of photonic devices for telecommunication applications. Opto-electronic devices such as high performance 1.55 mu m complex-coupled InGaAsP-InP distributed feedback (DFB) and 1.3 mu m uncooled AlInGaAs-InP lasers, the InGaAs-InP p-i-n photodetector on semi-insulating substrate, the 0.98 mu m InGaAs-GaAs-InGaP pumping laser, and 12-channel laser and detector arrays, are presented. Work on the development of in-house vertical integration for the fabrication of a 1.55 mu m single frequency transmitter, a 1.3 mu m multimode transmitter and receiver, and an Er-doped fibre amplifier, and their applications in system trials in the Taiwan National Information Infrastructure network, is described.