Using two focused 1064 nm pump beams with an intensity ratio 3:1 and a small crossing angle $\theta \approx {3.1}^\circ$, two-photon pumped (2PP) tristable lasing behavior has been observed in a dye (AMSPT) solution in dimethyl sulfoxide (DMSO). When each pump beam is incident alone, the measured pump energy threshold for 2PP lasing is ${\sim}{3.8}\;{\rm{mJ}}$. However, when the two pump beams are incident together, the energy of the strong pump beam varies from 4 to 10 mJ and the energy of the weak pump beam varies from 1.3 to 3.3 mJ. We then observe two simultaneous output lasing beams. However, when the strong pump beam is blocked, the weak pump beam is unable to create its own lasing output. This observed dual-beam lasing behavior can be well explained by a physical model of energy transfer between these two pump beams via the reflection of an induced Bragg grating. This observed dual-beam and tristable lasing behavior may be useful for future applications in an optical logical circuit or an optical computing system.

中文翻译：

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双光子泵浦双光束激光：三稳态操作

使用两个强度比为 3:1 和小交叉角$\theta \approx {3.1}^\circ$ 的聚焦 1064 nm 泵浦光束，在染料 (AMSPT) 中观察到双光子泵浦 (2PP) 三稳态激光行为) 的二甲亚砜 (DMSO) 溶液。当每个泵浦光束单独入射时，测得的 2PP 激光泵浦能量阈值为${\sim}{3.8}\;{\rm{mJ}}$. 然而，当两束泵浦光束一起入射时，强泵浦光束的能量在 4 到 10 mJ 之间变化，弱泵浦光束的能量在 1.3 到 3.3 mJ 之间变化。然后我们观察两个同时输出的激光束。然而，当强泵浦光束被阻挡时，弱泵浦光束无法产生自己的激光输出。这种观察到的双光束激光行为可以通过这两个泵浦光束之间通过感应布拉格光栅的反射进行能量转移的物理模型来很好地解释。这种观察到的双光束和三稳态激光行为可能对未来在光学逻辑电路或光学计算系统中的应用有用。