 Amplified spontaneous emission

Amplified Spontaneous Emission (ASE) is a phenomenon that occurs in laser systems, particularly in the context of fiber amplifiers and certain types of semiconductor lasers. It describes the process by which spontaneous emissions from atoms or molecules in an excited state are amplified through stimulated emission in a gain medium. Here's a breakdown of the key concepts: 1. **Spontaneous Emission**: When atoms or molecules return to their ground state from an excited state, they can emit photons spontaneously.