Breakthroughs in Photonics 2014: Coherent Vertical-Cavity Surface-Emitting Laser Arrays

Coherently coupled vertical-cavity surface-emitting laser (VCSEL) arrays exhibit novel optical properties, which can be exploited for applications. After a brief review of prior semiconductor optically coupled microcavity laser arrays, we discuss recent advances in photonic crystal implanted vertical-cavity laser arrays. We report the ability to tune these VCSEL arrays with appropriate geometry into coherence by ensuring spectral overlap between the resonance of each element of the array. Using the independent current injection into the elements of the coherently coupled array, the relative phase of the array elements and the output beam coherence can be tuned. Coherently coupled microcavity arrays are shown to offer the potential for ultrahigh-speed digital modulation.