Efficient Direct Laser Generation by Three‐Phonon‐Assisted Transition with Yb:YCOB Crystal

Electron–phonon-coupling effect can generate the direct lasing beyond fluorescence spectrum of gain medium, but laser efficiency is still low owing to weak multiphonon-coupling intensity. Herein, associated with three-phonon-assisted electron transitions 1100 nm, tunable generation from 1125 1155 nm and highly efficient continuous-wave lasers at 1131 1140 in a ytterbium-doped YCa4O(BO3)3 crystal are realized, by balancing intracavity loss phonon-determined gain. The maximum output power reaches 3.95 2.06 W corresponding slope 52.4% 39.1%, respectively, which represents highest solid-state this spectral range. More impressively, phonon-assisted vibronic exhibits wide-spectral tunability good stability. practical source underdeveloped range provided results, they helpful for development multiphonon-assisted inherent spectrum.