In　this　paper,　we　report　on　high　beam　quality　vertical-cavity　surface-emitting　lasers　(VCSELs)　featuring　a　monolithically　integrated　aspherical　microlens.　This　lens　is　fabricated　by　a　one-step　diffusion-limited　wet　etch　process.　VCSELs　with　microlenses　with　different　curvature　radius　are　designed,　fabricated,　and　characterized,　as　well　as　reference　VCSEL　devices　without　the　microlens.　Significant　improvement　of　beam　divergence　and　single-mode　performance　are　demonstrated　in　microlens　VCSELs.　The　divergence　angles　of　a　conventional　VCSEL　are　14.5　degrees,　16.0　degrees,　and　17.0　degrees　(full　width　at　D4　sigma)　at　2　mA,　3　mA,　and　4　mA,　respectively,　with　a　M-2　value　measured　to　be　6.9　at　3　mA.　Under　the　same　current　injection,　the　divergence　angles　of　a　comparable　VCSEL　with　a　micro-lens　(curvature　radius　of　31.8　mu　m)　are　reduced　to　4.8　degrees,　5.5　degrees,　and　5.7　degrees,　respectively.　The　M-2　value　of　the　lensed　VCSEL　is　as　low　as　1.9　at　3　mA.