In-phase, coherent photonic crystal vertical-cavity surface-emitting laser arrays with low divergence

Two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays are defined using an etched photonic crystal pattern and ion implantation. The 2 ?? 2 laser arrays are shown to operate in a single in-phase mode from threshold to maximum output power. The in-phase interference between the multiple lasers constituting the array form an angularly narrow, on-axis peak in the far field. These coherently-coupled laser arrays are of interest owing to their ease of fabrication and potential for creating low-diffraction beams with increased output power.