Polarization maintaining (PM) fibers are meant to maintain linear polarization along a preferred axis. A PM fiber can be seen as the fiber version of a very high order waveplate, designed with different refractive indices along two orthogonal axes. It is shown that monitoring the polarization of initially circularly polarized light sent through a PM fiber, leads not only to new sensing methods, but also to power control, saturable absorption, and optical path stabilization. Even at peak power levels not exceeding a few mW, nonlinear transmission is detected, with time constants in the microsecond range.

中文翻译：

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保偏光纤的低功率 (mW) 非线性

保偏 (PM) 光纤旨在沿优选轴保持线性偏振。保偏光纤可以看作是非常高阶波片的光纤版本，沿两个正交轴设计有不同的折射率。结果表明，监测通过 PM 光纤发送的初始圆偏振光的偏振，不仅会导致新的传感方法，而且还会导致功率控制、饱和吸收和光路稳定性。即使峰值功率水平不超过几毫瓦，也能检测到非线性传输，时间常数在微秒范围内。