Er:Yb:GdSr3(PO4)3 crystal with strong energy storage capacity as a 1.55 μm high-energy pulse laser medium for eye-safe laser ranging

Abstract

Er:Yb:phosphate glass is the only commercial material for high-energy 1.55 μm pulse laser presently, while its low thermal conductivity degrades the laser performances and applications. Benefitting from the similar spectral property to the Er:Yb:phosphate glass and higher thermal conductivity, Er:Yb:GdSr₃(PO₄)₃ cubic crystal is demonstrated to be a novel gain medium for high-energy 1.55 μm pulse laser in this work. End-pumped by a 975.1 nm laser diode, a quasi-continuous-wave laser around 1540 nm with a maximum peak output power of 1.76 W and a slope efficiency of 21 %, as well as a stable passively Q-switched 1535 nm pulse laser with an energy of 197 μJ, a repetition frequency of 10 Hz, a width of 8.3 ns, and a peak power of 23.7 kW were realized in an Er:Yb:GdSr₃(PO₄)₃ crystal. The first demonstration of high-energy 1.55 μm pulse laser in the Er³⁺/Yb³⁺ co-doped crystalline material provides an alternative solution for developing the detecting source of eye-safe laser rangefinder.