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?（）

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.

单项选择题For lasers with tightly controlled wavelengths, approximately how far apart are the centers of adjacent wavelengths when 100 GHz spacing is used in a DWDM system?（）

A. 0.4 nanometers
B. 0.6 nanometers
C. 0.8 nanometers
D. 1.2 nanometers
E. 1.6 nanometers

单项选择题If the power is 0 dBm, what is the power in mW?（）

A.0mW
B.1mW
C.10mW
D.1.5mW