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What is Population Inversion?
Population Inversion is a condition in which more atoms or ions in a gain medium occupy an excited energy state than a lower energy state. It is essential for achieving optical gain and enabling stimulated emission in lasers and optical amplifiers.
Population inversion is typically created by optical pumping, where energy from a pump source excites the active particles to higher energy levels.
HOW Population Inversion Works
Population inversion works by creating an excess of excited particles in a gain medium, allowing stimulated emission to dominate over absorption. This enables an optical signal to gain energy as it propagates through the medium.
Energy pumping
A pump laser supplies energy to the active atoms or ions, exciting them to higher energy states.
Population buildup
The excited particles accumulate in an energy level, creating a population distribution where stimulated emission becomes more likely than absorption.
Optical amplification
An incoming photon can trigger stimulated emission from an excited particle, producing an additional matching photon and increasing the optical gain.
