InP: Indium phosphide

LED: light-emitting diode

Long-haul: Links that span hundreds or even thousands of kilometers, typically served by 1,550-nm lasers.

Short-reach or short-haul: Generally, distances of 2 km or less.

TO can: Metallic packaging for VCSELs. Resembling an old-style transistor, the can consists of the nearly cylindrical VCSEL casing with spindly legs that connect the can to a pc board.

VCSEL: Vertical-cavity surface-emitting laser.

VSR: Very short reach, defined as distances of 300 m or less.