Lasing—the emission of a collimated light beam of light with a well-defined wavelength (color) and phase—results from a self-organization process, in which a collection of emission centers synchronizes itself to produce identical light particles (photons). A similar self-organized synchronization phenomenon can also lead to the generation of coherent vibrations—a phonon laser, where phonon denotes, in analogy to photons, the quantum particles of sound.
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Source: Phys.org