Scientific terminology laser is commonly written in small letters. It has even produced secondary acronyms such as LASIK (Laser-ASsisted in Situ Keratomileusis). A related acronym and neologism maser (Microwave Amplification by Stimulated Emission of Radiation) is much less known. Nevertheless, it is commonly written in small letters. On the contrary, acronym SPASER (Surface Plasmon Amplification by Stimulated Emission of Radiation) is capitalized. Many scientific acronyms or abbreviations reflect the artistic sense of their creators, e.g., etc. (see also List of astronomy acronyms). Scientific terminology Scientific terminology is the part of the language that is used by scientists in the context of their
Sound amplification by stimulated emission of radiation of direct semiconductors. The reasoning behind that comes from the fact that, due to the k-selection rule in semiconductors, interband transitions with the production of only one phonon can be only those that produce an optical phonon. However, optical phonons have a short life-time (they split into two due to anharmonicity) and therefore they add some important complications. Here we can note that even in the case of multi-stage process of acoustic phonon creation it is possible to create SASER. Examples of narrow-gap indirect semiconductors that can be used are chalcogenides PbTe, PbSe and PbS with energy gap 0.15 –