aser) Pronounced "vixel." A type of laser diode that emits light from its surface rather than its edge. A VCSEL's circular beam is easy to couple with a fiber, and due to its surface-emission architecture, can be tested on the wafer. VCSELs are also noted for their excellent power efficiency and durability. See laser diode
Surface Emitting and Edge Emitting
Note how the VCSEL emits light from its surface rather than its edge. Such an architecture allows for on-wafer testing.