Dependence of central-lobe output power on fill factor of an in-phase laser array

In a multiple-emitter diode laser array, coupled in-phase, a substantial amount of the output power is radiated in off-axis lobes. An approximate calculation of the central (0°) lobe output power of an in-phase array as a function of emitter width and array spacing is presented. The results for an array of Gaussian emitters indicate that a near-field fill factor of 70% is required to obtain 95% of the output power in the central lobe.