We present intra-fibre mode conversion from the antisymmetric LP₁₁ mode to the circularly symmetric LP₀₂ mode using a force-induced, long-period fibre grating accompanied by an in-line polarization controller. The field orientation of the incoming LP₁₁ mode is aligned to the antisymmetric perturbation in the fibre grating to activate resonant mode coupling. Mode conversion is achieved by applying pressure with a spatial period of 430 μm along an interaction length of 50 mm. We verify the mode conversion process by observing the far-field patterns of the fibre output and comparing the transmission power with and without a high-numerical aperture, narrow-core fibre. The intra-fibre mode conversion system with erasable and reconfigurable natures exhibits an insertion loss of 0.48 dB and a 3-dB bandwidth of 52 nm.

我们介绍了使用力感应式，长周期光纤光栅以及在线偏振控制器，将光纤从反对称LP ₁₁模式到圆形对称LP ₀₂模式的光纤模式转换。传入LP ₁₁的场方向模与光纤光栅中的非对称扰动对准，以激活谐振模式耦合。通过沿50 mm的相互作用长度施加430μm空间周期的压力来实现模式转换。我们通过观察光纤输出的远场模式并比较具有和不具有高数值孔径窄芯光纤的传输功率来验证模式转换过程。具有可擦除和可重新配置特性的光纤内模式转换系统表现出0.48 dB的插入损耗和52 nm的3 dB带宽。