Chapter 18 Spectrum magnification

A cascade of a Cd and a dC time lens can provide spectrum magnification, i.e., stretching along the frequency axis. The magnification factor is given by a relation between the modified dispersion parameters of the two fibers in the time lenses. A Gaussian input pulse generates a Gaussian output pulse, for example, 10 times broader and 10 times reduced in height. A rectangular input pulse generates an output pulse with a sinc-squared spectrum at the output magnified in width by the magnification factor and reduced in height by the same factor. For separating WDM channels that originally are closely spaced in the frequency domain, spectrum magnification and subsequent filtering of channels is shown to be useful.