单项选择题
What is an advantage of an externally modulated laser over a directly modulated laser？ （）
A. lower cost B. higher chirp C. easier to manufacture D. higher dispersion tolerance E. higher optical signal-to-noise ratio
单项选择题 Whatisthephenomenoncalledwheredifferentwavelengthsoflighttravelatdifferentspeeds？（）
单项选择题 WhichdevicecreatesanOEOconversion？（）
单项选择题 Whatisthedifferencebetweenthetransmittedpowerandthesensitivityofthereceiver？（）
