Sidelobe suppression of vertical coupler filter with an X-crossing configuration

An antiresonant reflecting optical waveguide (ARROW) type vertical coupler filter exhibiting low sidelobe charateristics is demonstrated. The sidelobe level of the filter has been suppressed by using an X-crossing arrangement to provide strength apodization along the device. The main sidelobe of the fabricated filter is measured to be less than -17 dB with the central wavelength in the 1.55 mu m region. An analysis procedure which combines the coupled mode theory with the finite difference mode solver is also presented to efficiently calculate the vertical coupler filter response.