You might have heard about lasers – devices that emit light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The term laser, in fact, is an acronym for Light Amplification by Stimulated Emission of Radiation. Now used in myriad ways, be it communication, medicine, entertainment or what not, laser, when first imagined, was originally called optical maser. For the maser was the forerunner of the laser and it was Charles Townes who was behind much of the theoretical work behind both.
Born in 1915 in Greenville, South Carolina, the U.S., Townes attended public schools and became interested in the sciences while still a youth. Having entered Furman University aged 16, Townes graduated with two degrees – a Bachelor of Science degree in Physics and a Bachelor of Arts degree in Modern Languages. It was during this time that physics first took hold of him, as he perceived it to have a “beautifully logical structure”.
Following a Masters degree at the Dukes University, which he obtained in 1936, Townes received his Ph.D. in Physics at the California Institute of Technology in 1939 with a thesis on isotope separation and nuclear spins. He was a technical staff with the Bell Telephone Laboratories till 1947, a period that coincided with World War II.
Radar bombing systems
The war effort required Townes to work and design radar bombing systems and he acquired a number of patents. After the war, Townes wanted to employ the microwave technique of wartime radar research to spectroscopy as he believed that microwaves could be used to study the structure of atoms, molecules and matter in general.
As a faculty member of the Columbia University, Townes set out on his research in microwave physics, studying interactions between microwaves and matter. It was in 1951 that Townes conceived his idea of the maser. It is believed that his breakthrough occurred while he was waiting for a restaurant to open and that he jotted down his outline of the plan on the backside of an envelope.
Action on molecular scale
Townes thought that action would be required on the molecular scale in order to effect amplification of very short wavelength radiation. He began working on a device with ammonia gas as the active medium in the following months, but it wasn’t until 1954 that he eventually achieved success.
When the first amplification and generation of electromagnetic waves by stimulated emission was obtained, Townes, along with his students, coined the term “maser” for the device – an acronym for Microwave Amplification by Stimulated Emission of Radiation.
Works with Schawlow
By 1958, Townes, with his brother-in-law, physicist Arthur Schawlow, had shown in theory that masers could be made to operate in the infrared and optical region. They even published joint papers on infrared masers and optical masers, which later went on to be called lasers.
Townes applied a patent titled “Production of electromagnetic energy” that same year, which he obtained on March 24, 1959. In this patent, Townes mentions an invention that relates to an “apparatus for amplifying and producing electromagnetic energy directly from excited molecules or atoms” and “the provision of a sustained microwave amplifier using directly the energy of molecular or atomic excitation”.
Months after Townes and Schawlow received their patent for the new idea of a laser in 1960, the first actual laser was demonstrated. And in 1964, Townes shared half the 1964 Nobel Prize in Physics for his path-breaking work along with two Russians, Aleksandr Prokhorov and Nicolai Basov, who had arrived at the idea of a maser independently.
