Evidence of nonradiative processes in Yb-doped oxoborate crystals by thermal lensing measurements

Summary from only given. Since they exhibit a low heat generation, ytterbium-doped materials turned out to be serious competitors of neodymium-doped materials for high power diode-pumped lasers. Because there is no excited-state absorption and upconversion processes, the only heat source is commonly admitted to be the quantum defect. As a consequence, thermal lensing is not expected to be different under lasing or non lasing conditions, provided the lasing wavelength is close to the average fluorescence wavelength. We herein relate thermal lensing measurements in diode-pumped Yb-doped oxoborate crystals: we observed strong differences between lasing and nonlasing conditions, proving that the quantum defect is not the only heat generating process.