Implant-defined　vertical-cavity　surface-emitting　laser　(VCSEL)　arrays　can　be　designed　to　operate　in　in-phase　mode.　However,　the　nonuniformities　in　fabrication　process　impact　the　resonance　selection　and　the　devices　do　not　follow　expected　trends.　Coherent　coupling　was　demonstrated　in　three-element　VCSEL　arrays　via　phase　tuning　of　elements.　In-phase　mode　and　out-of-phase　mode　were　both　achieved　in　most　of　the　arrays.　Moreover,　coherent　coupling　can　decrease　the　threshold　current　of　elements　in　the　array.　Improved　output　power　was　also　clearly　observed　when　the　array　operated　in　the　in-phase　mode.　Arbitrary　phase　combination　of　the　array　elements　can　be　obtained　via　the　phase　tuning.　This　technology　is　able　to　improve　the　reproducibility　and　practicability　of　the　implant-defined　coherently　coupled　VCSEL　array.　(C)　2016　Optical　Society　of　America