Reduction of filter sidelobe level by an X-crossing vertical coupled ARROW filter

An antiresonant reflecting optical waveguide (ARROW) type vertical coupler filter exhibiting low sidelobe characteristics 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-μm region.