Interleave filter with box-like spectral response and low chromatic dispersion

摘要

A density of channels as well as a bit-rate per channel in Wavelength Division Multiplexing (WDM) systems has been higher and higher to accommodate exploded traffic demand, which sets too demanding performance to optical components. In order to improve such a situation, interleave filtering technique, which separates the incoming spectrum into two complementary sets of periodic spectra, has been viewed with keen interest. To illustrate, consider the system shown in Figure. 1. It uses a "50-to-100 GHz interleave filter". Initially a single Arrayed- waveguide-grating (AWG) for n channels, spaced 100-GHz apart, is used. When another is added, the system is upgraded to 2n channels. Several types of interleave filters have been proposed, but to author's knowledge, none have met all the crucial requirements. These require- ments include a box-like spectral response and low chromatic disper- sion (CD). Among the most promising filter candidates, a Fourier transform-based Mach-Zehnder Interferometer (MZI)~((1)(2)) seems to be best because it predicts the potential of the arbitrary spectral response by using theoretical calculations. In this paper, for the first time, we propose and demonstrate a new Fourier-transform-based interleave filter with a box-like spectral response and low CD is proposed and demonstrated for the first time.