The amplification process in fiber optic amplifiers is based on the principle of stimulated emission. When the pump laser excites the dopant ions in the fiber, they transition to a higher energy state. It leverages a process called stimulated emission, where a fiber doped with rare earth elements (such as erbium, thulium, or ytterbium) is energized by a pump. Booster (power) amplifiers: Boost power into transmission fiber, low NF, high Psat. Note the presence of a gain peak around 1530nm and a semi-flat gain. This makes optical amplifiers essential in long-haul, ultra-long-haul, and submarine communication systems that form the backbone of today's global internet infrastructure.