Equalization of Gaussian-like spectra with optical lattice filters

We present a filter design scheme in which we use an all-fiber lattice filter to equalize Gaussian-like spectra. With a two-step design strategy, the designed equalization filter can flatten the Gaussian-like spectra in the maximally flat sense, and the spectrum ripples can be assessed quantitatively. The equalization performance is analyzed theoretically. It is also shown that the equalization performance can be improved only with an increased odd order of the lattice filter. As an illustrative example, the proposed scheme is applied to the design of an all-fiber equalization filter to flatten the output spectrum of a superluminescence light-emitting diode. Simulation and experimental results verify the theoretical analysis. © 2005 Optical Society of America OCIS codes: 060.2380, 230.3670, 230.1150, 070.6020.