ABSTRACT
In September 1957 Charles Hard Townes had written a draft with the general idea of what could be the first maser operating at optical frequencies, the so-called optical maser. Townes visited Bell Laboratories, where he was aiding work on masers, and lunched with Arthur L Shawlow to whom he described his efforts to construct an infrared or optical maser. The work by Shawlow and Townes created considerable interest and many laboratories started to search for possible materials and methods for optical masers. Townes, with his group at Columbia, started efforts to build an optical maser with potassium. Townes and Shawlow were the first to publish a detailed and exhaustive proposal which subsequently led to the construction of various types of lasers. At the forefront among the proponents of the idea to build an optical generator that exploited the principle of stimulated emission was Valentin Aleksandrovic Fabrikant who in the Soviet Union made his proposal in the 1940s.
