采用半经典密度矩阵理论计算了单纵模(SLM)和多纵模(MLM)脉冲光抽运重水(D_2O)分子亚毫米波(SMMW)激光三能级系统的抽运信号的吸收系数和亚毫米波激光信号的增益系数,利用迭代法数值计算了亚毫米波激光信号的频谱特性和输出光强,对频谱精细结构和激光过程的规律进行了深入的研究和比较。研究结果表明,在超辐射情况下,多纵模光抽运D_2O与单纵模光抽运相比,前者的亚毫米波激光谱线较宽;在腔式的情况下,单纵模和多纵模光抽运D_2O的亚毫米波激光谱线都进一步展宽,在频谱曲线上均呈现与多纵模结构对应的多个尖峰。 The absorption coefficients of the pump signals of single-longitudinal mode (SLM) and multi-longitudinal mode (MLM) pulsed light pumping heavy water (D 2 O) molecular submillimeter wave (SMMW) laser three- The gain coefficient of the millimeter wave laser signal is calculated by using the iterative method. The spectral characteristics and output light intensity of the submillimeter laser signal are calculated. The fine structure of the frequency spectrum and the laser process are studied and compared. The results show that in the case of super-radiation, the multi-longitudinal mode optical pumping D 2 O has a wider linewidth than the single-mode optical pumping. In the case of cavity mode, the single longitudinal mode and multi-longitudinal mode Longitudinal mode optical pumping of D 2 O sub-millimeter wave laser lines are further broadened, in the spectral curve are presented with multiple longitudinal mode structure corresponding to multiple spikes.