“Unlocking the Light: The Genius Behind Lasers and Their Astonishing Secrets Revealed!”
Excited by his discovery, Maiman rushed to publish a paper titled Optical Maser Action in Ruby in the Physical Review, but to his shock it was immediately rejected. This rejection has become part of laser history lore, and is often blamed on a conservative and unimaginative scientific establishment failing – or refusing – to recognize the significance of Maiman’s discovery. After all, as Maiman’s assistant Irnee D’Haenens quipped at the time, for many years the laser was seen as a ‘solution looking for a problem’ with few apparent applications outside of scientific research. The truth, however, is far less exciting. According to Simon Pasternack, an editor at the Physical Review at the time, he rejected Maiman’s paper simply because he had already published a very similar paper earlier that year. In any case, a shortened version of Maiman’s paper was readily accepted by the journal Nature, and his discoveries soon came to the attention of the scientific community.
But while Maiman’s ruby laser was an important technical breakthrough, it was somewhat limited in its capabilities. To understand why, it is necessary to understand in greater detail just how lasers actually work. As we’ve covered earlier in this video, lasers work by using photons to stimulate electrons in atoms to jump from one energy level to another and back, causing the atoms to release photons of the same energy as the original. In the simplest systems such as Townes’ original ammonia maser, there are just two energy levels: the ground state and the excited state. Maiman’s laser, however, had three energy levels: the ground state, the excited state, and a metastable state between the two. When the ruby was stimulated or “pumped” by the flash lamp, the electrons in the atoms jumped first to the excited state then spontaneously dropped to the metastable state, where they remained for a considerable length of time. This longevity was key to the laser’s operation, as it allowed a sufficient population of excited atoms to accumulate to achieve a population inversion – a state in which the photons created by stimulated emission outweighed those absorbed by ground-state atoms. The problem, however, was that once an atom released a photon, it immediately dropped back into the ground state, which soon became oversaturated and prevented population inversion from taking place. For this reason, Maiman’s laser could only produce light in short pulses. Producing a continuous beam required the development of a four-level laser with two metastable states.
