Er^(3+)掺杂CaYAlO_(4)晶体光谱和激光性能研究

Spectral and Laser Properties of Er^(3+)-Doped CaYAlO_(4)Crystals

采用提拉法成功生长出掺杂浓度(原子数分数)为15%和30%的Er∶CaYAlO_(4)晶体。研究了Er∶CaYAlO_(4)晶体偏振光谱性能和激光特性。测试了室温下晶体的偏振吸收光谱、偏振荧光光谱和荧光衰减曲线。CaYAlO_(4)基质的无序性使吸收谱和发射谱呈现宽带特征。15%Er∶CaYAlO_(4)晶体在σ偏振和π偏振的发射截面分别为1.22×10^(-20)cm^(2)(2712 nm)和0.71×10^(-20)cm^(2)(2754 nm),半峰全宽(FWHM)分别为152和167 nm。随着Er^(3+)掺杂浓度升高,4 I 11/2和4 I 13/2能级的荧光寿命均有不同程度的下降,而且上下能级寿命比值(τlower/τupper)大幅减小。能量传递上转换过程ETU1不仅可以抑制自终止效应还可以提高2.7μm辐射跃迁量子效率。974 nm LD泵浦源的激发下,透过率1.5%的输出镜对应的激光性能最佳。c切15%Er∶CaYAlO_(4)晶体在2720 nm处最大输出功率为358 mW,斜效率为15.4%。

Er^(3+)-doped CaYAlO_(4)crystals with the doping concentration(atomic fraction)of 15%and 30%were successfully grown by Czochralski method.The polarized spectral and laser properties of Er∶CaYAlO_(4)crystals were studied.The polarized absorption spectra,polarized emission spectra and fluorescence decay curves were measured at room temperature.The disorder of CaYAlO_(4)crystal results in broadband characteristics of absorption and emission spectra.The emission cross section of 15%Er∶CaYAlO_(4)is determined to be 1.22×10^(-20)cm^(2)at 2712 nm forσpolarization and 0.71×10^(-20)cm^(2)at 2754 nm forπpolarization,with a full width at half maximum(FWHM)of 152 and 167 nm,respectively.As Er^(3+)concentration increases,fluorescence lifetime of 4 I 11/2 and 4 I 13/2 energy levels decreases in different degrees,and lifetime ratio(τlower/τupper)greatly reduces.The energy transfer upconversion ETU1 not only suppresses self-termination effect but also improves quantum efficiency of 2.7μm radiative transition.Under 974 nm LD excitation,laser property for output couple mirror with a transmittance of 1.5%is best.The maximum output power is 358 mW at 2720 nm with a slope efficiency of 15.4%in c-cut 15%Er∶CaYAlO_(4)crystal.