Highly efficient and high-power yellow fiber laser

It is a challenge to balance the high-power laser output and simple structure in the visible region. Traditional schemes are hampered by high costs and complex configurations. In this study, to fully explore the power scaling capability of visible fiber lasers, the impact of the pump sources' brightness and pump configurations on the performance of the fiber-based yellow laser was investigated. The obtained slope efficiency reaches a maximal value of 49.8% owing to the high-brightness pump laser and excellent gain extraction enabled by counter-propagation pump configuration, while further power scaling was limited by the available power of a single high-brightness laser diode. To optimize the output power and thermal management, the bi-directional pump configuration was introduced for visible fiber laser generation for the first time, where a maximal output power of 2.57 W at 575 nm was achieved, which is more than two-fold higher than the output power previously reported. The laser slope efficiency is as high as 40.6%. To the best of our knowledge, this work represents the record power and slope efficiency in Dy³⁺-doped single-clad fiber laser operating in the yellow spectral region. To enable further power scaling beyond the limits of core pumping, we designed a double-clad fiber and predicted a tenfold increase in output power via numerical simulations.