external modulator

是光收发模块还是光调制器？
原文是
The
optoelectronic devices covered in this document include active devices such as lasers
(Laser Diodes [LDs] and Laser Modules [LMs]), Light Emitting Diodes (LEDs and Light
Emitting Modules [LEDMs]), photodetectors (Photodiodes [PDs] and Photodetector
Modules [PMs]), and external modulators.

是外调制器，光调制器，就是对激光器输出的光进行调制

那段英文描述的好像是模块，包含。。。
其中，external modulator是外调制器