We report the molecular beam epitaxial growth of narrow gap dilute nitride InAsN alloys onto GaAs substrates using a nitrogen plasma source. The photoluminescence (PL) of InAsN alloys with N-content in the range 0 to 1% which exhibit emission in the mid-infrared spectral range is described. The sample containing 1% N reveals evidence of recombination from extended and localized states within the degenerate conduction band of InAsN. A comparison of GaAs and InAs based material shows little change in PL linewidth such that the change in substrate does not cause significant reduction in quality of the epilayers. The band gap dependence on N content in our material is consistent with predictions from the band anti-crossing model. We also report the growth of InAsSbN/InAs multi-quantum wells which exhibit bright PL up to a temperature of 250 K without any post growth annealing. Consideration of the power dependent PL behaviour is consistent with Type I band alignment arising from strong lowering of the conduction band edge due to N-induced band anti-crossing effects.