Title: Dispersion in ultrafast lasers

Hong Wee Tan


Abstract: The evolution of ultrafast laser=05 technology has now reached =
a point where the performance of these lasers is determined by the qualit=
y of dispersion control. If a pulse propagates through a dispersive mediu=
m, the shape and in particular, the duration of the pulse may be changed.=
 To understand how this comes about, we shall first consider the simple c=
ase of a Gaussian pulse propagating through a medium with significant sec=
ond order dispersion amplitude.  With this understanding, we come to reco=
gnize that any element through which light propagates is a potential sour=
ce of material dispersion; this includes the gain medium, modulators and =
even the air path between components. For ultrafast lasers, higher order =
dispersive (third, fourth...) effects become important. Consequently, to =
compensate for these dispersive effects, suitable interferometers, prism =
sequences, chirped dielectric mirrors or even combinations of these optic=
al elements are often employed. A brief discussion on how each of these t=
echniques works will be given.

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