Abstract
We present experimental data characterizing the first-observed transverse mode with y-junction structures in a broad-area (20 μm in diameter) oxide-confined vertical-cavity surface-emitting laser at a 22.3 mA injection current which is larger than the thermal roll-over point. The formation of the y-junction structured pattern, which can be observed in far-field images, is due to an interaction between adjacent high-order transverse modes.