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Dilute nitride GaInNAs and GaInNAsSb alloys grown on GaAs have quickly become excellent candidates for a variety of lower cost 1.2-1.6 μm lasers, optical amplifiers and high-power Raman pump lasers that will be required to power the Internet and advanced communications systems capable of delivering multi-Gbit/s data rates to the desktop. Two particularly critical devices are vertical-cavity surface-emitting lasers (VCSELs) which must operate at high data rates (≥10 Gbit/s), uncooled over a broad thermal operating range and high power (≥500 mW) edge-emitting lasers for Raman amplifier pumps. Despite the fact that these materials are grown in a metastable regime, and there are still many remaining challenges, progress has been both rapid and very promising. Some of the material challenges include the limited solubility of N in GaAs, nonradiative defects that are caused by either or a combination of N incorporation, low growth temperature, and ion damage from the N plasma source. N and Sb add a unique set of properties to this metastable alloy; however, this significantly increases the complexity of its characterisation. The addition of Sb significantly improves the epitaxial growth and optical properties of the material at wavelengths longer than 1.3 μm and broadens the range of In and N composition alloys that can be grown. By adding Sb to the alloy, luminescence has been greatly enhanced between 1.3 and 1.6 μm where normally poor quality material results. Progress in overcoming some of the material challenges is described, particularly GaAsNSb against GaNAs QW barriers, plasma-source ion damage and progress in realising record-setting edge-emitting lasers and the first VCSELs operating at 1.5 μm based on GaInNAsSb QWs grown by solid-source MBE on GaAs.