Compact ARROW-type vertical coupler filter

Compact wavelength filter utilizing the vertical coupling between a conventional ridge waveguide and a 3-D ARROW is proposed and demonstrated. Compact size and narrowband performance are achieved utilizing the large difference of waveguide dispersion between the 3-D ARROW and the ridge waveguide at single mode. A polyimide ridge waveguide was stacked on a stripe lateral confinement ARROW in an intersecting configuration with the interaction length of about 1 mm, and -3-dB linewidth of 5.5 nm was experimentally achieved.