SIDELOBE-SUPPRESSION OF GRATING-ASSISTED CODIRECTIONAL COUPLER FILTERBY SELECTIVE-AREA GROWTH

We propose and demonstrate a technique for the sidelobe suppression in an InP/InGaAsP semiconductor grating-assisted codirectional coupler ( GACC) optical filter. By employing selective area growth (SAG) in an I nP separation layer, the epitaxial film thickness was spatially contro lled so that the coupling coefficient distribution between two wavegui des has the Hamming functional form. Most sidelobes are suppressed bel ow -12 dB, which is low compared to the conventional GACC filters.