日韩欧美亚洲 _ 欧美亚洲一区 _ 日本亚洲欧美 _ 亚洲精品欧美 国产白袜脚足J棉袜在线观看_亚洲熟妇av一区二区三区_久久天天躁狠狠躁夜_精品众筹模特私拍在线

單項(xiàng)選擇題

Why are the 1300 nm and 1550 nm regions of the fiber spectrum primarily used for optical communications?()

A. They are both regions of lowest loss.
B. They are both regions of low reflections.
C. They are both regions of low index of refraction.
D. They are both regions of low chromatic dispersion.
E. They are both regions of low Polarization Mode Dispersion (PMD).

微信掃碼免費(fèi)搜題