VCSELs and How to Keep Them Cool
Vertical-cavity surface-emitting lasers (VCSELs) are a type of semiconductor laser that emits a circular, low-divergence beam of light perpendicular to the surface of the chip, as opposed to edge-emitting lasers that emit parallel to the chip surface. This beam quality simplifies optical system design and improves coupling efficiency. VCSELs are characterized by their unique structure, which consists of a thin layer of active semiconductor material sandwiched between two highly reflective mirrors.