采用水平区熔法生长了碲(Te)掺杂浓度(质量百分比)分别为0.05%,0.1%,0.5%,1%,2%的硒化镓(GaSe)晶体，并分别对掺杂浓度为0.01%，0.07%,0.38%,0.67%,2.07%的GaSe:Te晶体的光学性能进行了表征。首次研究了GaSe∶Te晶体中刚性层声子模式的转换。吸收光谱测试结果表明：当Te掺杂浓度小于0.38%时，振动中心位于0.59 THz附近的E′(2)刚性模式吸收峰强度可达最大值，这一过程与GaSe∶Te晶体光学性能的提高密切相关。但Te掺杂浓度的进一步提高会导致E′(2)刚性模式吸收峰强度逐渐减弱，当Te掺杂浓度为1%时，E′(2)刚性模式吸收峰基本消失。这两个过程与GaSe:Te晶体光学质量的下降密切相关。因此，E′(2)刚性模式吸收强度达到最高时对应的掺杂浓度即是GaSe∶Te晶体中Te的最佳掺杂浓度，光整流产生太赫兹过程证实了此结论的正确性。

ε-GaSe crystals are grown with the stoichiometric GaSe of 0.05%, 0.1%, 0.5%, 1% and 2%(mass percent) Te and are characterized by GaSe∶Te(0.01%, 0.07%, 0.38%, 0.67% and 2.07%(mass percent)) crystals. The transformation of the rigid layer phonon modes with doping is studied for the first time. The absorption peak of the rigid mode E′(2) centered at ~0.59 THz is rising up in the intensity till reaching a maximal value on the first stage of the doping concentration less than 0.38%(mass percent). This process correlates well with the improvement in the optical property. Further doping is resulting in the decrease of the intensity till vanishing the E′(2) absorption peak at 1%(mass percent) Te. Simultaneously with the E′(2) absorption peak decreasing, the absorption peak of the rigid mode E′(2) centered at 1.78 THz is rising up in the intensity. The two processes correlate well with the degradation in the optical quality of GaSe∶Te crystal. The doping level that results in the highest intensity of the absorption peak of the rigid layer mode E′(2) is proposed as a criterion in the identification of the optimal Tedoping in GaSe crystal that is confirmed by THz generation via optical rectification.