Considerable research effort has been devoted recently to the incorporation of RE ions, in particular Er3+, into wide bandgap III-nitride semiconductors. Significant progress has been achieved in terms of material growth and the understanding of fundamental optical properties of GaN:Er using photoluminescence (PL), photoluminescence excitation (PLE), and electroluminescence (EL) spectroscopies. Initially, poor crystalline quality of doped material resulted in very poor emission efficiency in the visible and infrared regions. Several growth techniques are now available to grow Er-doped GaN with reasonable crystalline quality and significantly improved optical emission at 1.54 4m has been demonstrated. In this chapter, we summarize major research on Er-doped GaN grown by different techniques. Very recent progress on Er-doped InGaN alloys, in particular those grown by metal organic chemical vapor deposition (MOCVD) in the authors' laboratory, is reviewed. Electrical and optical properties are described as well as preliminary demonstrations of emitter and optical waveguide amplifiers operating in a 1.54 4m communication window. Perspectives and future challenges in material issues, design and fabrication of novel photonic devices of Erdoped nitride semiconductors for applications in optical communications are discussed.