An integratable polarization-independent tunable filter for WDM systems: the multigrating filter

After a review of the design principles, we present new experimental and theoretical results about the multigrating filter (MGF), a tunable channel selection filter for wavelength division multiplexed (WDM) transmission systems. Bit error rates mere measured at 2.5 Gb/s for single- and multichannel operation of a packaged polarization independent four-channel MGF with integrated amplifiers. The single-channel results are compared with theory. A monolithic tunable channel dropping component has also been fabricated by integrating two MGF's, a splitter, and amplifiers. Bit error rates measurements are presented for optical (at 2.5 Gb/s) and electrical on-chip (at 622 Mb/s) channel dropping in single- and multichannel operation.