设计了一种端面泵浦扭转模腔双频Nd∶YAG激光器系统, 该激光器以偏振分光棱镜作为偏振元件, Nd∶YAG晶体的两端各放置一个四分之一波片, 在垂直于腔轴的平面内旋转其中一个波片, 输出连续可调谐双频激光, 最大调谐范围为一个激光谐振腔纵模间隔.采用琼斯矩阵进行了理论分析, 得出频率分裂量与波片转角成正比关系.实验研究了扭转模腔选模特性、纵模分裂特性和偏振特性.结果表明：两个四分之一波片正交时, 激光器输出线偏振单纵模激光, 扭转模腔失谐时, 单纵模分裂为两个正交的线偏振模, 实验获得的最大频率分裂量为3 GHz.实验结果与理论分析一致.该连续可调谐双频Nd∶YAG激光器结构简单, 可用于激光干涉测量和微波光电子等领域.

A twisted-mode cavity end-pumped dual-frequency Nd∶YAG laser has been presented. The polarizing beam splitter is used as the polarizer and two quarter-wave plates are placed on each end of the gain medium Nd∶YAG crystal. The frequency difference of the dual-frequency laser can be continuously tuned through the whole cavity free spectral range, by rotating one of two quarter-wave plates in the plane perpendicular to the cavity axis. The theoretical analysis based on Jones matrices is made that the frequency difference is proportional to the rotation angle of the wave plate. The characteristics of twisted-mode cavity mode selection, mode splitting and polarization have been investigated experimentally. The results show that laser is output with the linearly polarized single longitudinal mode when the two quarter-wave plates are perpendicular, and the single longitudinal mode splits into two modes which are orthogonally linearly polarized modes while the twisted-mode cavity is detuning. The largest frequency difference obtained is about 3 GHz. Experimental results match well with the theoretical analysis. Such a continuous tunable dual-frequency Nd∶YAG laser with simple structure will find wide applications in the fields of laser interferometry, and microwave photoelectronics, etc.