A switchable quintuple-wavelength erbium-doped fiber laser using the linear-cavity configuration is proposed and demonstrated experimentally at room temperature. It is composed of two Sagnac loops that act as the cavity mirrors in the resonant cavity and contain two kinds of multimode fibers with different core diameters (50 and 62.5 µ m). The two loops become two comb filters to jointly excite the multi-wavelength output. By using the effects of multimode interference and polarization hole-burning, and after adjusting a polarization controller, the laser can switch flexibly to output nine different kinds of modes from single-wavelength to quintuple-wavelength. All lasing lines with a narrow linewidth of less than 0.25 nm have an optical signal-to-noise ratio of more than 14 dB. The laser has good power uniformity shows good stability with respect to the wavelength and peak power.

中文翻译：

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基于具有不同纤芯直径的多模光纤的五波长EDF激光器

提出了一种采用线性腔结构的可转换五波长掺光纤激光器，并在室温下进行了实验验证。它由两个Sagnac环路组成，它们充当谐振腔中的腔镜，并包含两种具有不同纤芯直径（50和62.5 µm）的多模光纤。这两个环路成为两个梳状滤波器，共同激发多波长输出。通过利用多模干涉和偏振烧孔的效果，并在调整了偏振控制器之后，激光器可以灵活切换以输出从单波长到五波长的九种不同模式。所有窄线宽小于0.25 nm的激光线的光信噪比均大于14 dB。