We propose and experimentally demonstrate a novel switchable quadruple-wavelength CW erbium-doped fiber laser, using a linear cavity structure. It is composed of two Sagnac loops that act as cavity mirrors in the resonant cavity. The left loop consists of a 3 dB fiber coupler (FC), a squeezed polarization controller (PC), and a chirped fiber grating. The right loop consists of a 10 dB FC, the same PC and a length multimode fiber with a core diameter of 62.5 μm. The two loops based on different operation principles become two comb filters to jointly excite the multiwavelength output. On the role of the polarization hole burning effect, after adjusting the two PCs, the laser can switch flexibly to output fourteen kinds of different modes from a single wavelength to the quadruple wavelength. All lasing lines, with a narrow linewidth less than 0.28 nm, have the optical signal-to-noise ratio of more than 20 dB. The laser with good power uniformity shows better stabilities of the wavelength and peak power.

我们提出并实验证明了一种使用线性腔结构的新型可切换四波长连续波掺fiber光纤激光器。它由两个Sagnac环路组成，在谐振腔中充当腔镜。左环路包括一个3 dB光纤耦合器（FC），一个压缩偏振控制器（PC）和一个线性调频光纤光栅。右环路包括一个10 dB FC，同一台PC和一根长度为62.5μm的多模光纤。基于不同工作原理的两个环路成为两个梳状滤波器，共同激发多波长输出。在偏振光烧孔效果的作用下，调整两台PC后，激光器可以灵活切换，以输出从单一波长到四倍波长的14种不同模式。所有窄线宽小于0.28 nm的激光线，具有大于20 dB的光信噪比。具有良好功率均匀性的激光器显示出更好的波长和峰值功率稳定性。