Far-field distribution of double-heterostructure diode laser beams

Previous analytical solutions for the far-field of a double-heterostructure diode laser have been restricted in scope because of several ad hoc assumptions, which were incorporated at rather early stages of the analysis. Based on a rigorous solution of the Helmholtz equation, it is shown that the commonly used assumption of separability of the field distributions along the two transverse axes of a diode may be misleading under certain conditions. Furthermore, the theoretical upper limit on the F.W.H.M. divergence angle is shown to be 65.5°, which is more realistic than the previous estimate of this parameter.