A six-mode scrambler based on cascaded side-wall long-period-grating waveguides on a silica planar lightwave circuit (PLC) platform is proposed for mode-division-multiplexing (MDM) transmission. The device can be fabricated with only one-step etching since it does not use a surface grating. A mode-dependent loss (MDL) of the system is estimated and the MDL can be reduced with a multiple scrambling operation. Two gratings proposed here and a fiber-pigtailed module containing these gratings are fabricated and the expected proof-of-concept mode scrambling operation is confirmed. It is found that the connection between few-mode fiber (FMF) and PLC chip seems to be the dominant loss of the module. Considering these losses, the measured results are in good agreement with the calculated results.

提出了一种基于二氧化硅平面光波电路 (PLC) 平台上级联侧壁长周期光栅波导的六模加扰器，用于模分复用 (MDM) 传输。由于该器件不使用表面光栅，因此只需一步蚀刻即可制造。估计系统的模式相关损耗 (MDL)，并且可以通过多次加扰操作来减少 MDL。这里提出的两个光栅和包含这些光栅的光纤尾纤模块被制造出来，并确认了预期的概念验证模式加扰操作。发现少模光纤（FMF）和PLC芯片之间的连接似乎是模块的主要损耗。考虑到这些损失，实测结果与计算结果非常吻合。