New design of multiple-active-region electrically-pumped VCSELs and edge-emitting lasers

A novel injection multi-active-region cascade laser with high output power, low threshold, small beam divergence, and high inter-modal discrimination is described. The cascade laser is formed by a periodic structure of stacked double-heterostructure diodes electrically connected by low-resistance tunnel junctions. The laser cavity is designed to match the nodes of the optical mode with the tunnel junctions and the antinodes - with the gain layers. We have considered both the cascade vertical-cavity surface-emitting laser (cascade VCSEL) and the cascade edge-emitting laser. In the multi-layer VCSEL with the multi-active-region cavity, the combined effect of increased net gain and distributed feedback allows an increased output from the Fabry-Perot resonator with mirrors of reduced reflectivity. The edge-emitting cascade laser represents a phase-locked laser array with a strong overall inter-element optical coupling. Maximum packing density of the active regions can be achieved in the common confinement cascade laser with weak optical confinement within a single array element. High inter-modal discrimination in the periodic laser structure with concentrated gain and absorption allows us to design a laser that operates in the in-phase mode with the tunnel junctions and gain layers placed in every second node and antinode of the mode, respectively.