Narrowing a laser beam's linewidth by a factor of over ten thousand using Raman scattering of light from vibrating diamond crystals

https://www.eurekalert.org/news-releases/1091068

linewidth measures beam's frequency/ color purity maintenance, narrower = more monochromatic/ spectrally pure... tested deliberately noisy input Brillouin laser beam with linewidth exceeding 10 MHz. hitting mm-scale diamond crystal in carefully designed cavity, Raman scattering narrowed output beam to 1 kHz limit their detection system... Raman technique transfers timing irregularities into diamond crystal vibrations, dissipated, leaving behind narrow waves... quantum computing, atomic clocks, gravitational wave detection"