Which type of laser is characterized by emitting light from its surface?

The vertical cavity surface emitting laser (VCSEL) is characterized by emitting light from its surface, which is a distinguishing feature of this type of laser. Unlike edge-emitting lasers, which emit light from their edges, VCSELs have a design that allows the light to be emitted perpendicular to the plane of the chip. This is achieved through the use of mirrors that reflect light within the cavity, directing it out through the surface.

One of the advantages of VCSELs is that they can be fabricated in arrays, which is useful for applications such as optical communications and sensing. Their surface emission also leads to simpler packaging and cooling solutions compared to edge-emitting lasers.

In contrast, edge-emitting lasers and diode lasers typically emit light along a linear path from the edges or an active region, and fiber lasers guide light within a fiber optic medium, rather than emitting it directly from a surface. Therefore, the unique emission characteristics of VCSELs make them particularly suited for specific applications in opto-electronic systems.