求翻译：虽然全光开关已经研究了近半个世纪,但是能够用于光纤通信系统的全光开关至今没有实现。这是因为光纤通信对全光开关的性能要求很高。例如,要求光开关的开关功率至少要达到或小于毫瓦量级；要求开关时间至少要达到和小于皮秒量级；此外还要求光开关的吸收小、尺寸小、结构简单、成本低廉等。虽然多年来曾经研究过的全光开关的种类很多，但是在宏观尺度下能够满足以上要求的全光开关极少，光纤光栅全光开关几乎是唯一有希望的。是什么意思？

Although all-optical switching has been studied for nearly half a century, but all-optical switching for optical fiber communication system has not achieved. This is because the optical fiber communication demanding the performance of all-optical switching. For example, switching power requirements

Although all-optical switch has been studied by nearly half a century, but it can be used for optical fiber communications system, all-optical switch has not yet occurred. This is because fiber optic communication to all-optical switch of the performance requirements are very high. For example, requ

Although the entire light switch has already studied the near half century, but can use in the optical fiber communications system the entire light switch not realizing until now.This is very high because of the optical fiber communications to the entire light switch performance requirement.For exam

All-optical switching has been studied for nearly half a century, but could be all-optical switch for optical fiber communication systems have not been achieved. This is because performance requirements for all-optical switching of optical fiber communication is very high. For example, light switch

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