High repetition rate π-polarized 1084 nm passively Q-switched Nd:MgO:LiNbO3 laser based on 888 nm thermally boosted pumping

Abstract

We report a high-repetition-rate π-polarized 1084 nm passively Q-switched (PQS) Nd:MgO:LiNbO3 (Nd:MgO:LN) laser under 888 nm thermally boosted pumping. The 888 nm pumping is selected based on Nd:MgO:LN crystal absorption and energy level properties. Under 813 nm pumping, the continuous wave (CW) 1084 nm average output power (AOP) increased to 2.85 W. After that, 1084 nm is suppressed and gradually disappears as the pump power increases. At the same time, the 1093 nm AOP increases, and 4.4 W of 1093 nm laser is obtained. In contrast, under 888 nm pumping, the CW 1084 nm laser AOP of 5.16 W is obtained. The thermally boosted pumping can eliminate quantum defects caused by conventional 813 nm pumping non-radiative transitions and suppress unmatched σ-polarized 1093 nm output. Moreover, the Cr4+: YAG is replaced into the resonant cavity as the output mirror to obtain 1084 nm pulsed laser output. AOP with different initial transmission (T0) on laser output characteristics is measured under the compact resonant cavity structure. Finally, an AOP of 3.52 W pulsed laser with a repetition rate of 24.43 kHz and the highest peak power of 5.26 kW is obtained when T0 = 87 %, and the absorbed pump power is 20.87 W. The optical conversion efficiency is 16.87 %, and the slope efficiency is about 29.38 %.