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为了获得较窄增益带宽、较大光强的太赫兹辐射,尝试了利用TEACO2激光器对6 W可调谐连续波CO2种子激光实行双程光放大实验,以期望获得长脉冲、高峰值功率的抽运光.通过实验,获得了大约30倍的放大系数,放大光输出功率随种子光注入功率的增加而增加,其中10 P(20)支线表现更加突出,并且被放大的激光支线半峰全宽在14μs左右.基于这种长脉冲抽运源,建立了一种产生脉冲太赫兹的动力学模型,给出了产生太赫兹辐射的饱和抽运光强表达式,确定了抽运光的光强范围.另外,通过对动力学模型含时解的推导,得到了太赫兹增益介质吸收抽运光能量的表达式.分析表明:对于强抽运光,这种长脉冲激光可能更适合充当重分子太赫兹增益介质的抽运源;而对于较弱抽运光,几乎不能形成转动能级间的粒子数反转,因而无太赫兹辐射产生.
In order to obtain terahertz radiation with a narrower gain bandwidth and larger intensity, an attempt was made to implement a double-pass optical amplification experiment on a 6 W tunable continuous-wave CO2 seed laser using a TEACO2 laser in the hope of obtaining pumping with a long pulse and a high peak power Light.According to experiments, the amplification factor is about 30 times, and the output power of the amplified light increases with the increase of the seed light injection power, of which 10 P (20) branch lines are more prominent and the full width at half maximum 14μs. Based on this long-pulse pumping source, a dynamic model of generating pulsed terahertz (THz) is established. The expression of saturated pumping light intensity is given and the range of light intensity In addition, the expression of energy absorbed by the terahertz gain medium is obtained by deducing the time - dependent solution of the dynamical model. The analysis shows that for strong pumping light, the long - pulse laser may be more suitable as a heavy molecular too Hertz gain medium pumping source; and for weak pumping light, almost can not form the rotation between the number of particles in the inversion, so no terahertz radiation.