The lasing threshold is the lowest excitation level at which a laser's output is dominated by stimulated emission rather than by spontaneous emission. Below the threshold, the laser's output power rises slowly with increasing excitation. Above threshold, the slope of power vs. excitation is orders of magnitude greater. The linewidth of the laser's emission also becomes orders of magnitude smaller above the threshold than it is below. Above the threshold, the laser is said to be lasing. The term "lasing" is a back formation from "laser," which is an acronym, not an agent noun.
Read more about Lasing Threshold: Theory
Famous quotes containing the word threshold:
“The free man is a warrior.—How is freedom measured among individuals, among peoples? According to the resistance that must be overcome, according to the trouble it takes to stay on top. The highest type of free man must be sought where the highest resistance is constantly overcome: five steps away from tyranny, close to the threshold of the danger of servitude.”
—Friedrich Nietzsche (1844–1900)