Investigation of Near-Field and Far-Field Distribution for Design Optimization of a 4 4 InGaAs/GaAs Vertical-Cavity Surface-Emitting Laser Array

We report the results of our investigation on the near-field and far-field distribution of the optical emission on in the design optimization of a 4 $\times$ 4 InGaAs/GaAs vertical-cavity surface-emitting laser (VCSEL) array. We examined the effect of the refractive index variation and the inter-element spacing on the near-field and far-field distribution of the optical emission modes in positive-index-guided VCSEL arrays, using numerical simulation. Our results demonstrate that a strong transverse-mode overlapping with poor inter-modal discrimination occurs in the near-field emission pattern of a VCSEL array for a small index-step and a small inter-element separation shorter than one wavelength. However, the modal discrimination can be improved in an array for a large refractive index step even if the array has a small inter-element separation. In addition, a stronger near field and a higher optical power can be obtained from positive-index-guided VCSEL arrays having a larger index-step under the conditions of other parameters being equal. KCI Citation Count: 0