Who is known for proposing the foundational concepts that lead to the invention of lasers?

The person known for proposing the foundational concepts that led to the invention of lasers is Albert Einstein. In 1917, Einstein published a paper detailing the theory of stimulated emission, which is the essential principle underlying how lasers work. Stimulated emission occurs when an electron in an excited state transitions to a lower energy state, emitting a photon in the process. This concept is crucial because lasers operate on the principle of amplifying light through stimulated emission.

Einstein's work laid the theoretical groundwork for the development of laser technology, which was realized decades later in the form of the first laser in 1960. His contributions to quantum theory and the understanding of light and energy transitions were pivotal in the evolution of laser technology. While other figures in the choices contributed significantly to physics and technology, none had the specific theoretical insight into light behavior that was necessary for the development of lasers in the way Einstein did.