Dengler Simon A, Engelbrecht Rainer, Schmauss Bernhard
Opt Express. 2021 Oct 11;29(21):34629-34640. doi: 10.1364/OE.437903.
To our knowledge, we are the first to measure the absolute value of the backscattering coefficient of a standard 1 mm core-diameter, multimode (MM) step-index (SI) polymethylmethacrylate (PMMA) polymer optical fiber (POF) for the spectral range of 450 nm to 700 nm. Our optical time domain reflectometer (OTDR) setup consists of a femtosecond supercontinuum laser with an acousto-optical filter as a tunable light source with short pulses and a time-correlated single-photon counting system as a receiver with a high dynamic range. The backscattering coefficient is calculated from the ratio between the energy within the fiber end reflex and the distributed backscattering level. We also measured the spectral attenuation with our OTDR setup and compared it with a standardized measurement method. At the attenuation minima within the measured spectral range the backscattering level of a 1 ns pulse is about -46 dB at 520 nm, -48 dB at 570 nm, and -51 dB at 650 nm. We were also able to show by the observed wavelength dependence that Rayleigh scattering causes a majority of the scattering.
据我们所知，我们是首个测量标准1毫米芯径、多模（MM）阶跃折射率（SI）聚甲基丙烯酸甲酯（PMMA）聚合物光纤（POF）在450纳米至700纳米光谱范围内后向散射系数绝对值的。我们的光时域反射仪（OTDR）装置由一台飞秒超连续激光器和一个声光滤波器组成，该声光滤波器作为具有短脉冲的可调谐光源，以及一个时间相关单光子计数系统作为具有高动态范围的接收器。后向散射系数由光纤末端反射内的能量与分布式后向散射水平之间的比率计算得出。我们还用我们的OTDR装置测量了光谱衰减，并将其与标准化测量方法进行了比较。在测量光谱范围内的衰减最小值处，1纳秒脉冲的后向散射水平在520纳米处约为 -46分贝，在570纳米处为 -48分贝，在650纳米处为 -51分贝。我们还通过观察到的波长依赖性表明，瑞利散射是散射的主要原因。
