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John Runions wrote:

> Ok, I've got to ask.  What is prechirp?  I've never heard the term before
>today and I want to be able to use it in conversation at parties.  Over
>and out, John.

A fibre - like any glass - has dispersion which means that red
light travels faster than blue.  A femtosecond pulse has a spread
of wavelengths (of a few nm) and since these travel at different
speeds the pulse becomes longer by the end of the fibre.  Prechirping
means retarding the longer wavelengths so that the shorter ones
are in front.  Then they all come together again at the end of the
fibre.  Obviously the amount of prechirp has to be carefully matched
to both the length of the fibre and the pulse length.  A fiddly
business and best avoided if possible!

                                                Guy

Assoc. Prof. Guy Cox,                 ooOOOOOOoo
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