We experimentally demonstrate spatial beam self-cleaning in an Yb-doped graded-index multimode fiber taper, both in passive and active configurations. The input laser beam at 1064 nm was injected for propagation from the small to the large core side of the taper, with laser diode pumping in a counterdirectional configuration. The Kerr effect permits to obtain high-beam quality amplification with no accompanying frequency conversions. As a result, our nonlinear taper amplifier may provide an important building block for multimode fiber lasers and amplifiers.

中文翻译：

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具有减速非线性的锥形掺镱GRIN多模光纤中的空间光束自清洁

我们通过实验证明了在无源和有源配置中，掺镱渐变折射率多模光纤锥度中的空间光束自清洁。注入 1064 nm 的输入激光束以从锥形的小芯侧向大芯侧传播，激光二极管以逆向配置泵浦。克尔效应允许在没有伴随频率转换的情况下获得高光束质量放大。因此，我们的非线性锥形放大器可为多模光纤激光器和放大器提供重要的构建模块。