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Researchers are making quick progress toward high-frequency sound lasers that could be used for precise and non-destructive medical imaging. (Credit: Alan Stonebraker)
These are schemes for phonon amplification and lasing: (Top) Two coupled microcavities are excited by an optical pulse traveling through an optical fiber (blue). (Center) Pump photons entering through the fiber are converted to lower energy photons and coherent phonons. At a threshold pump power, phonon gain exceeds phonon loss resulting in phonon lasing. (Bottom) Phonon amplification in a superlattice. Tunneling of electrons from one quantum well to the next is accompanied by phonon emission. When a strong phonon wave is applied, it leads to phonon amplification. (Credit: Alan Stonebraker)
Fifty years after the invention of the optical laser, two separate research groups have independently made important steps toward making phonon lasers — a type of laser that emits very high-frequency, coordinated sound rather than light waves — a reality. The studies, published in the journal Physical Review Letters, could lead to a completely new kind of laser that could find interesting applications in medical imaging.
Read the full article: Sound lasers inch closer to reality
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