Ultrashort Laser Pulse Phenomena, 2nd Edition

592 Selected Applications

channels at frequency intervals of 100 GHz, which is the free spectral range of

such an etalon.

In the example of trans-Pacific communication, the frequency of the etalons

at successive amplifiers was shifted by 0.18 GHz at each successive amplifier

spaced 26 km apart. The total shift over the 9,000 km trans-Pacific distance is

still smaller than the 100 GHz frequency spacing between channels [43]. The

soliton pulse duration was 16 ps at 1557 nm. The fiber had an average dispersion

D = 0.5 ps/(nm km). Recall (cf. Fig. 8.4) that the parameter D = dk





/dλ =

−(2πc

0

/λ

2

)k





is generally used to characterize fibers, because it relates directly

to the group delay (in ps) per nm of bandwidth and per km propagation length.

Although this