Cr^(4+): YAG被动调Q与激发态吸收饱和

Excited State Absorption Saturation of Cr 4+ ∶YAG and Its Passive Q switch Performance

运用速率方程计算了Ｃｒ４＋ＹＡＧ晶体的基态吸收、激发态吸收与入射脉冲的能量密度和强度的关系。在测量晶体透过率的实验中，发现Ｃｒ４＋ＹＡＧ晶体的激发态吸收趋于饱和。理论计算与实验数据拟合给出了包括基态吸收截面，激发态吸收截面和寿命等参数。在用Ｃｒ４＋ＹＡＧ对脉冲式ＮｄＹＡＧ激光器被动调Ｑ的实验中，得到脉宽５ｎｓ、能量９０ｍＪ的激光脉冲，并且发现这种调Ｑ与Ｃｒ４＋ＹＡＧ的激发态吸收饱和直接相关。

Dependences of ground state absorption and excited state absorption of Cr 4+ ∶YAG upon fluence and intensity of input laser pulses are calculated based on the rate equation. Measuring transmission of this crystal, we discovered that its excited state absorption tended to be saturated. Key parameters are obtained by matching the theory calculation with experimental data. The Nd∶YAG laser with 5 ns pulsewidth was operated and found which is directly relevant to excited state absorption saturation of Cr 4+ ∶YAG .