On-axis far-field emission from two-dimensional phase-locked vertical cavity surface-emitting laser arrays with an integrated phase-corrector

We have fabricated large, two-dimensional (2D) arrays of optically pumped, phase-locked vertical cavity surface-emitting lasers that emit more than 50% of their light in a central on-axis lobe. The emission of the arrays was modified from the usual four-lobed far-field of 2D coupled arrays by incorporation of a binary phase-shift mask on the surface of the array. The array consists of Fabry-Perot resonators comprising GaAs/AlGaAs quantum wells surrounded by AlAs/AlGaAs quarterwave mirrors with a multiple order AlGaAs phase-delay layer on the top mirror stack. The phase-shift layer was etched away on alternating elements of the array. The resulting on-axis emission had an angular width of 2°for an array of approximately 100 elements.