2. Surface emitting laser (VCSEL)

Principle and uses

Instead of conventional side-emitting lasers —Edge-Emitting semiconductor Lasers (EEL) — laser sources known as "Vertical-Cavity Surface-Emitting Lasers" (VCSEL) have been studied and realized by using laser cavity mirrors in such a way that light is emitted perpendicular to the junction (figure 1 ).

These VCSEL lasers are used in particular as optical sources for LAN (local area network) telecommunications networks, thanks to two important properties: their low threshold current and the ease with which such laser arrays can be built, combined with the low cost of these structures.