The authors report on the design and performance of an all-optical vertical-cavity semi-conductor gate (VCSG) based on dilute nitride (GaInNAs/GaAs) quantum wells, proposed for performing AND/OR or NAND/NOR logic functions. In particular, the authors analyse the effect of non-linear refractive index variation on the overall non-linear characteristic of the device. Compared to typical InP-based non-linear gates GaAs-based devices incorporating dilute nitride active regions are a step forward towards reducing the fabrication complexity and relaxing the design constrains by employing high-quality GaAs/AlAs distributed Bragg reflectors. The authors develop a predictive model of VCSG relying on numerical simulation. Trade-off between the operation bandwidth and the modulation depth is found out associated to a variation of the refractive index for different optical injection conditions.