Click the Exhibit button. Which type of multiplexer is shown in the exhibit?（）

单项选择题The dispersion of a non-zero dispersion shifted fiber is 6 ps nm*km at 1550 nm and 10 ps nm*km at 1610 nm. What is the minimum dispersion compensation required if an L-Band DWDM signal travels through 200 km of fiber and has a dispersion tolerance of 1800 ps nm?（）

A. none
B. -600 ps/nm
C. -200 ps/nm
D. +200 ps/nm
E. +600 ps/nm

单项选择题If the dispersion of a given fiber is 17ps nm*km at 1550 nm and zero at 1310 nm, then what is the accumulated dispersion of an ITU wavelength after it travels 200 km?（）

A.0 ps/nm
B.340 ps/nm
C.200 ps/nm
D.3400 ps/nm
E.More information is needed.

多项选择题What are three factors that limit the maximum distance of an amplified optical signal without regeneration? （）(Choose three.)

A. fiber dispersion
B. signal attenuation
C. transmitter power
D. amplifier bandwidth
E. receiver dispersion tolerance

多项选择题Click the Exhibit button. When designing a DWDM system with multiple amplified spans, a pre-amp is needed at Site B to （）. (Choose three.)

A. offset the OADM loss at site b 
B. overcome the high multiplexer loss at site a 
C. amplify signal levels after the high loss through Fiber Span 1
D. adjust add channels at site B to be at the same level as the passthrough channels
E. ensure that the per channel power is higher than the minimum needed for the post-amp at Site b

单项选择题How is a Thin Film filter fabricated?（）

A. The glass core is doped with an Erbium in periodic segments of the fiber.
B. Layers of high index ?and low index ?material are deposited on a glass substrate.
C. Thin layers of silica glass are placed onto wafers to produce a prism-like effect.
D. Fiber is etched with an ultraviolet laser that is precisely spaced for specific wavelength filtering.