Free-running modes for gain-guided diode laser arrays

We present a numerical model for directly calculating the eigenmodes of multiple-stripe gain-guided diode laser arrays, which includes the effects of both carrier diffusion and heating in the active region. Comprehensive calculations of the eigenmodes of a CW gain-guided array using this model are directly compared to experimental observations on commercial ten-stripe arrays. These numerical and experimental results show that, contrary to popular wisdom, gain-guided arrays are characterized by a large number of eigenmodes, not limited to the number of elements in the array. In addition, our results show the importance of including the refractive index perturbation arising from junction heating, which dramatically alters both the character and the gain of the array modes.