Quasi-continuous-wave diode-pumped microchip yellow–orange lasers with peak power over 100 W

Abstract We present quasi-continuous-wave (QCW) diode-pumped yellow–orange microchip lasers based on cooperative multi-phonon coupling and self-frequency doubling in Yb 3+ -doped YCa 4 O(BO 3 ) 3 crystals. QCW pumping at 100 Hz introduces cooling intervals that effectively suppress thermal accumulation. By optimizing the pump duty cycles, microchip yellow lasers at 565 nm and orange lasers at 590 nm were realized with peak powers of 125 and 102 W, respectively. The corresponding single-pulse energies were 4 mJ (yellow) and 2.4 mJ (orange). To the best of our knowledge, these results represent the highest reported peak power and single-pulse energy among all QCW yellow–orange microchip lasers. As a demonstration, the compact orange source was used to excite the fluorescent dye Cyanine 3.5, yielding a 20-fold enhancement in photoluminescence compared to conventional green lasers, indicating its great potential for flow cytometry applications with new laser wavelengths.