保偏单模耦合器 ppsm polarization preserving single mode: 保偏单模光纤polarization-preserving coupler: 保偏耦合器single polarization coupler: 单偏振耦合器single mode coupler: 单模耦合器single polarization single-mode fiber: 单偏振单模光纤下载手机词典可随时随地查词查翻译