Coherent laser arrays from bottom-surface vertical-cavity surface-emitting lasers

Vertical-cavity surface-emitting lasers (VCSELs) are among the best choices for high beam quality semiconductor lasers. By designing a VCSEL array for uniform current injection and having the output coupler on the substrate side of the laser cavity, the laser will more easily operate in the fundamental Gaussian mode. This type of laser is referred to as a bottom-emitting VCSEL. Bottom-emitting VCSELs show promising results for two-dimensional coherent arrays where multiple laser elements are operated in an optically coupled configuration. With independent current injection, the rich behavior of the bottom-emitting coherent VCSEL array can be explored and controlled