TOWARD THE IDEAL CODIRECTIONAL BRAGG FILTER WITH AN ACOUSTO-OPTIC-FILTER DESIGN

We present a novel design scheme based on the GeI'fand-Levitan-Marchenko inverse-scatter method for an acousto-optic tunable filter having an almost-ideal bandpass spectrum. We find that the ideal filter characteristics of flat-top with unity transmission and no side-lobes are in principle asymptotically possible in a properly designed codirectional Bragg filter. We propose physical schemes of achieving such characteristics in the acousto-optic tunable filter design. Filters having this desirable characteristic are of immense importance in improving the cross-talk performance in optical networks employing the wavelength-division-multiplexing scheme. We then discuss design specifics and simulated performances, and present a new optimization formula.