利用非线性偏振旋转效应可在能量对称的非线性光纤环镜中获得强度相关损耗输出,具有该特性的非线性光纤环镜可作为强度均衡器来抑制室温条件下的掺铒光纤中的模式竞争。对这种环镜在多波长掺铒光纤激光器中的应用进行了研究,分析了入射偏振态和环镜内双折射对非线性光纤环镜输出特性的影响,研究了激光腔内光场的偏振条件以及对多波长激光系统的作用,并在L波段获得了3 dB范围内13条波长输出,波长间隔为1 nm,单波长半个小时内的功率波动小于0.6 dB。通过调整非线性光纤环镜引入的强度相关损耗的大小可以控制多波长的数目和频谱位置。

The intensity-dependent loss output characteristic of the symmetric nonlinear optical loop mirror (NOLM) can be induced by the nonlinear polarization rotation effect. The application of symmetric NOLM as the intensity equalizer to suppress the mode competition in multiwavelength eribum-doped fiber laser is studied. The influences of both input polarization and birefringence on the output characteristic are analysed. The polarization conditions in this laser cavity are analysed. A multiwavelength eribum-doped fiber laser with this device is porposed and demonstrated successfully. In the L-band 13 lasing wavelengths,with 1nm spacing in 3 dB range,has been obtained,single-wave length power fluctuation of each laser line is less than 0.6 dB within 0.5 h. Both the laser line number and its multiwavlength operation spectral region can be controlled by adjusting the intensity-dependent loss in the cavity.