Resonant cavity LEDs (RCLEDs) are a viable and low-cost alternative light source to lasers for optical communication systems in the 1.3 mu m O-band. Most work in this area has been conducted on InP-based material, which is inherently costly, devices often require cooling and the refractive index contrast for constructing mirrors is low. Here, we demonstrate a high-performance GaAs-based RCLED using a dilute nitride GaInNAs active layer emitting in the 1.3 mu m wavelength window. While previous 1.3 mu m RCLEDs have used metallic mirrors on the back of the device, we exploit the high refractive index contrast of the GaAs/AlAs system to place Distributed Bragg mirrors on both sides of the active layer and achieve superior performance. The external quantum efficiency of the devices is 20% and the full width at half maximum of the emission spectrum is 5.2 nm at room temperature, into a narrow angular cone. The emission power from an 88 mu m diameter aperture is 0.5 mW, which, together with the narrow spectral linewidth, makes the device suitable for deployment in a coarse Wavelength Division Multiplexing (WDM) communications system.