Electrically Parallel Three-Element 980 nm VCSEL Arrays with Ternary and Binary Bottom DBR Mirror Layers

To meet the performance goals of fifth generation (5G) and future sixth generation (6G) optical wireless communication (OWC) and sensing systems, we seek to develop low-cost, reliable, compact lasers capable of sourcing 5–20 Gb/s (ideally up to 100 Gb/s by the 2030s) infrared beams across free-space line-of-sight distances of meters to kilometers. Toward this end, we develop small arrays of electrically parallel vertical cavity surface emitting lasers (VCSELs) for possible future use in short-distance (tens of meters) free-space optical communication and sensing applications in, for example, homes, data centers, manufacturing spaces, and backhaul (pole-to-pole or pole-to-building) optical links. As a starting point, we design, grow by metal–organic vapor phase epitaxy, fabricate, test, and analyze 980 nm top-emitting triple VCSEL arrays. Via on-wafer high-frequency probe testing, our arrays exhibit record bandwidths of 20–25 GHz, optical output powers of 20–50 mW, and error-free data transmission at up to 40 Gb/s—all extremely well suited for the intended 5G short-reach OWC and sensing applications. We employ novel p-metal and top mesa inter-VCSEL connectors to form electrically parallel but optically uncoupled (to reduce speckle) arrays with performance exceeding that of single VCSELs with equal total emitting areas.