Hou Wentao, Kalusniak Sascha, Püschel Stefan, Tanaka Hiroki, Xu Jun, Tang Jun, Kränkel Christian
Opt Express. 2025 Feb 24;33(4):6799-6807. doi: 10.1364/OE.550678.
We present growth, spectroscopy and efficient laser operation of the cubic fluoride crystal Er:BaF at 2.8 µm. An Er(3.6 at.%):BaF crystal was grown by the vertical Bridgman method. We reveal the thermal conductivities of pure BaF and Er:BaF crystals for different temperatures. The temperature-dependent cryogenic absorption spectra were investigated in the near-infrared range, and we determined the energetic positions of the Stark levels of the upper and lower laser multiplets I and I, respectively. A strong absorption peak at 971.5 nm and a broad gain bandwidth around 2.7-2.9 µm with a large emission cross section at 2732 nm were found. Under pumping with an optically-pumped semiconductor laser (OPSL) at 971.5 nm, we obtained 0.4 W of output power at a wavelength of 2786 nm with a slope efficiency of 31%. The slope efficiency is the highest in reported for 3 µm lasers based on Er:BaF at present.
我们展示了立方氟化物晶体Er:BaF在2.8微米波长下的生长、光谱特性及高效激光运转。采用垂直布里奇曼法生长了Er(3.6原子百分比):BaF晶体。我们揭示了纯BaF晶体和Er:BaF晶体在不同温度下的热导率。研究了近红外范围内随温度变化的低温吸收光谱，并分别确定了上、下激光多重态I和I的斯塔克能级的能量位置。发现了971.5纳米处的强吸收峰以及2.7 - 2.9微米附近的宽增益带宽，在2732纳米处有较大的发射截面。在971.5纳米的光泵浦半导体激光器（OPSL）泵浦下，我们在波长2786纳米处获得了0.4瓦的输出功率，斜率效率为31%。目前，该斜率效率是基于Er:BaF的3微米激光器中报道的最高值。
