钬铥双掺钨酸镱钾激光晶体光谱参数计算

采用顶部籽晶提拉法（TSSG）生长了钬铥双掺钨酸镱钾（KHo_0.04Tm_0.06Yb_0.9（WO₄）₂）激光晶体。测试了该晶体的吸收及荧光光谱，计算了其光谱参数。实验结果表明：该晶体在890~1 000 nm范围吸收带较宽，半峰宽为90 nm，计算了主峰1 000 nm处吸收截面为16.92×10^-20 cm²；Tm³⁺在1 690~1 812 nm范围存在较宽的吸收带，半峰宽为118 nm，易于实现Yb→Ho、Yb→Tm、Tm→Ho的能量传递。根据Judd-Ofelt理论，计算了该晶体的光谱强度参数。根据Tm³⁺、Ho³⁺、Yb³⁺离子能级图，讨论了产生1 750~2 200 nm荧光发射的3种能量传递方式。最后计算了主峰2 030 nm处受激发射截面为3.47×10^-20 cm²，表明该晶体可作为2 μm波段优异的激光增益介质。

Spectral Parameter Calculation of Ho3+, Tm3+ Co-doped KYb(WO4)2 Laser Crystal

KHo_0.04Tm_0.06Yb_0.9(WO₄)₂ laser crystal was grown by the top seeded solution growth (TSSG) method. The absorption and fluorescent spectra of the crystal were measured, and the spectral parameters were calculated, too. The experimental results show that there is a broader absorption band at the range of 890-1 000 nm with a full width at half maximum (FWHM) of 90 nm. The absorption cross section of main emission peak at 1 000 nm is 16.92×10^-20 cm². Meanwhile, Tm³⁺ ions in the crystal have a wider absorption band at 1 690-1 812 nm with a FWHM of 118 nm. Therefore, the energy transfer of Yb→Ho, Yb→Tm, Tm→Ho can be easily achieved. The spectral strength parameters of the crystal were calculated based on the Judd-Ofelt theory. According to the energy level diagram of Tm³⁺, Ho³⁺ and Yb³⁺ ions, three kinds of energy transfer modes at 1 750-2 200 nm emission were discussed. The stimulated emission cross section of main emission peak at 2 030 nm is 3.47×10^-20 cm², which indicates that the crystal can be used as an excellent laser gain medium at the range of 2 μm.