What is the phenomenon called where different wavelengths of light travel at different speeds？（）

单项选择题WhichdevicecreatesanOEOconversion？（）

A. amplifier
B. attenuator
C. regenerator
D. light emitter
E. optical switch
F. optical receiver
G. fiber-optic cable

单项选择题Whatisthedifferencebetweenthetransmittedpowerandthesensitivityofthereceiver？（）

A. OSNR
B. dispersion
C. attenuation
D. power budget
E. amplifier spacing
F. four wave mixing

多项选择题Whichthreetechnologiesareusedtoreducechromaticdispersionaccumulationinfiber-optictransmissionsystems？（）

A. PIN photodiodes
B. zero-chirped lasers
C. Erbium-doped fiber amplifiers
D. dispersion compensating fiber
E. dispersion compensating Bragg grating

单项选择题Whyarethe1300nmand1550nmregionsofthefiberspectrumprimarilyusedforopticalcommunications？（）

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）.

多项选择题Whatthreeincombinationarefactorsthatcancausefour-wavemixinginfiber-opticcables？（）

A. low optical powe
B. high optical power
C. few optical channels
D. many optical channels
E. low chromatic dispersion
F. high chromatic dispersion
G. too much power differential in the optical channels