This paper presents an extensive numerical analysis of 1.3-mu m wavelength wafer-fused vertical-cavity surface-emitting lasers (VCSELs) incorporating intracavity patterning. Using a 3-D, self-consistent model of the physical phenomena in VCSELs, supported by experimental results used for parameter calibration, we investigate the influence of arch- and ring-shaped intracavity features with a broad range of geometrical parameters on the modal behavior of the VCSEL. To design and optimize the devices, we used intracavity patterning that provides very strong discrimination of higher order modes, pushing them out from the active region. This mechanism makes possible single mode operation under a broad range of currents and could potentially enhance the single-mode output power of these devices.