We experimentally demonstrated the phenomenon of period-multiplying pulses in the self-mode-locking Nd:YVO4 laser. With a fixed cavity length of 50 mm and the input mirrors in the resonator with radii of curvature of 100 mm, 200 mm, and 500 mm, the mode-locked pulses with pulse periods 4 times, 6 times and 10 times the fundamental mode-locked pulse period are observed respectively. Besides, by tilting the angle of the output mirror to control the spatial distribution of transverse modes, the switching between the period-multiplication state and its harmonic self-locking state can be achieved. Numerical simulations further confirm that this period-multiplying phenomenon results from the simultaneous locking of multi-longitudinal and multi-transverse modes. This study is of great significance for understanding the complex transverse dynamics in the self-mode-locking lasers.

中文翻译：

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Nd:YVO4 激光器全自锁模产生倍增脉冲

我们通过实验证明了自锁模 Nd:YVO4 激光器中的周期倍增脉冲现象。固定腔长为50 mm，谐振腔内输入镜的曲率半径为100 mm、200 mm和500 mm，脉冲周期为基模4倍、6倍和10倍的锁模脉冲分别观察锁定脉冲周期。此外，通过倾斜输出镜的角度来控制横模的空间分布，可以实现倍增状态与其谐波自锁状态之间的切换。数值模拟进一步证实了这种倍增现象是由多纵向和多横向模态同时锁定引起的。这项研究对于理解自锁模激光器中复杂的横向动力学具有重要意义。