Er:Yb:Sc2Si2O7 Crystal with Superior Thermal Conductivity and Strong Energy Storage Capacity for kHz-Level High-Peak-Power 1.55 μm Eye-Safe Pulsed Microlaser

Stable high-repetition-frequency and high-peak-power eye-safe 1.55 μm microlasers are highly desirable as pivotal light sources for portable sensing technologies in both civilian and defense fields. However, the existing Er3+/Yb3+ co-doped gain medium fails to simultaneously deliver high thermal conductivity and strong energy storage capability, which becomes a critical bottleneck limiting the development of such microlasers. Herein, a Sc2Si2O7 crystal with a dense structure and unique [Si2O7]6− ditetrahedral unit was designed as a host for Er3+/Yb3+ co-doping and grown by the Czochralski method. Enabled by its intrinsic structural advantages, the Er:Yb:Sc2Si2O7 crystal possesses a high thermal conductivity of 9.2−9.7 W m−1 K−1, a strong energy storage capacity associated with a 7.0 ms fluorescence lifetime of the 4I13/2 upper laser level, and a high Yb3+ → Er3+ energy transfer efficiency of 87%. By constructing a compact sandwich-like Er:Yb:Sc2Si2O7 microlaser, a 2.1 W continuous-wave 1565 nm laser with a slope efficiency of 23% and stable 1536 nm passively Q-switched pulsed lasers with repetition frequencies of 1−3 kHz, duration of 2.46 ns, and peak powers exceeding 20 kW were obtained. This work develops a novel high-performance gain material for high-repetition-frequency, high-peak-power 1.55 μm pulsed microlasers, offering a promising light source for high-speed scanning and long-distance portable detection systems.