Continuously diode-pumped passively $Q$Q-switched eye-safe 1537  nm Er:Yb:Lu₂Si₂O₇ pulse laser

It is still a technical challenge to obtain a 1.55 µm passively $Q$Q-switched ${{\rm Er}^{3 + }}/{{\rm Yb}^{3 + }}$Er³⁺/Yb³⁺ pulse laser with high energy and high repetition frequency, especially when it is end-pumped by a continuous-wave 0.98 µm diode laser. Benefitting from its long fluorescence lifetime of the $^4{{\rm I}_{13/2}}$⁴I_13/2 upper laser level and high thermal conductivity, ${\rm Er}:{\rm Yb}:{{\rm Lu}_2}{{\rm Si}_2}{{\rm O}_7}$Er:Yb:Lu₂Si₂O₇ crystal may be an excellent gain medium for realizing a high energy and high repetition frequency 1.55 µm pulse laser. At a continuous-wave absorbed pump power of 6.1 W, a 1537 nm pulse laser with energy of 45.5 µJ, repetition frequency of 1.32 kHz, and duration of 25 ns was first, to the best of our knowledge, realized in an ${\rm Er}:{\rm Yb}:{{\rm Lu}_2}{{\rm Si}_2}{{\rm O}_7}$Er:Yb:Lu₂Si₂O₇ crystal.