Who theorized the concept of stimulated emission?

The concept of stimulated emission was theorized by Albert Einstein in 1917. His work laid the foundation for understanding how lasers operate. Einstein's theory suggested that when an atom is excited to a higher energy state and then interacts with a photon of light, it can be stimulated to drop back down to a lower energy state, emitting a second photon that is coherent with the first. This principle is crucial in laser technology because it enables the amplification of light, which is the core function of a laser.

Other contributors to quantum theory, like Bohr, provided insights into atomic structure and energy levels but did not specifically articulate the concept of stimulated emission. Ted Maiman is known for creating the first working laser but was not involved in the theoretical development of stimulated emission. Stern and Sognnaes also contributed to the understanding of optical phenomena but did not originate the stimulated emission theory. Einstein's work remains fundamental to the principles of laser operation and quantum mechanics.