Laser performance of a 966  nm LD side-pumped Er,Pr:GYSGG laser crystal operated at 279  μm

Abstract

We demonstrate a 966 nm laser diode (LD) side-pumped Er,Pr:GYSGG laser crystal operated at 2.79 μm under a high repetition rate. The lifetimes of the upper level I4 and lower level I4 are 0.66 and 0.85 ms, respectively. The laser performance under different repetition rates and pulse widths is experimentally studied with the optimal cavity structure. A maximum output power of 8.86 W is achieved at 125 Hz and 200 μs pulse widths, corresponding to the slope efficiency of 14.8% and electrical-to-optical efficiency of 7.7%. With increasing frequency from 50 to 200 Hz, the slope efficiency varies from 24.7% to 11.7% operated at a 125 μs pulse width. Moreover, the Mx2/My2 factors of 7.52/7.59 and Θ/Θ far-field divergences of 16.1/16.5 mrad are also measured. The results indicate that a high-performance 2.79 μm laser could be realized on the Er,Pr:GYSGG radiation resistant crystal by deactivation and LD side-pumping.

2.79 μm laser performance of a 968 nm LD side-pumped Er:LuYSGG mixed crystal

“…8. The beam quality factor M 2 is calculated from the following equation: 26 where ω is the beam waist diameter, Θ is the far-field divergence, and λ is the laser wavelength. The laser beam quality M 2 factors in the x and y directions are fitted to be 7.04 and 7.12.…”

“…Thus, more pump power may be consumed to compensate for these losses. 26 The longer duration of a single pump pulse is beneficial to the accumulation of upper particles. However, in the highfrequency pump mode, the longer pulse width corresponds to the higher duty cycle, and more waste heat is accumulated in the crystal rod, resulting in the increase of the thermal lensing effect and limiting the enhancement of output power.…”

“…24,25 In 2008, Zhao et al demonstrated an LD sidepumped Er,Pr:GYSGG crystal with a maximum output power of 8.86 W at 125 Hz and 200 μs pulse width. 26 In 2021, Hu et al obtained an average output power of 15.59 W at 500 Hz and 70 μs pulse width on an LD side-pumped YSGG/Er:YSGG/ YSGG bonding rod with concave end-faces. 27 The above works indicate that the LD side-pumped mode is advantageous to achieving a high performance 2.79 μm laser.…”

Laser Performance of Neodymium- and Erbium-Doped GYSGG Crystals

“…Recently, Zhao et al adopted the diode side-pumping scheme to pump Er,Pr:GYSGG, and realized a maximum output power of 8.66 W with a slope efficiency of 14.8% at a repetition rate of 125 Hz and pulse width of 200 µs. These impressive results indicate that Er,Pr:GYSGG crystals have great potential in high-power 2.79 µm laser generation by deactivation and LD side-pumping [48]. successfully grew high-quality Er,Pr:GYSGG crystals with the Czochralski method [9].…”

Evaluation of Growth, Thermal, and Spectroscopic Properties of Er3+-Doped CLNGG Crystals for Use in 2.7 μm Laser

“…By far, various Er 3+ -doped gain materials had been reported, such as the garnet (crystals and ceramics) YAG [5], GGG [6], LuGG [7], YGG [8], YSGG [9][10][11][12], GSGG [13,14], the sesquioxide (crystals and ceramics) Y 2 O 3 [15,16], Lu 2 O 3 [17], and the fluoride (crystals, ceramics, and fibers) CaF 2 [18,19], SrF 2 [20], LiYF 4 [21], ZBLAN [22]. However, the fluorescence lifetime of the upper laser level 4 I 11/2 is much shorter than that of the lower laser level 4 I 13/2 , which is considered to be self-terminating, making the population inversion difficult and impeding laser oscillations.…”