Fig. 12: Examples of waveguide-to-waveguide couplers utilizing cantilever coupling.
From: Advances in waveguide to waveguide couplers for 3D integrated photonic packaging
a–c Reference 164 (reprinted with permission from ref. 164 ©Optical Society of America). In (a), a schematic of the cantilever coupler. In (b), a side view of the packaged system showing the cantilevers on the top and bottom die and the measurement apparatus. In (c), the wavelength dependence of the cantilever coupler is shown for the TE and TM modes. d–f Reference 168 (reprinted with permission from ref. 168 ©Optical Society of America). In (d), a cross sectional view shows the material system of the ion implanted cantilever coupler for different cantilever taper lengths (VCW(40) stands for vertically curved waveguide with 40-μm long cantilever). In (e), a perspective view is shown of cantilever couplers fabricated using ion implantation. In (f), data shows the loss coupling from the cantilever to a lensed optical fiber for different polarizations and cantilever taper lengths (doubling these values can give a rough estimate for waveguide-to-waveguide coupling). In (g), schematics of a SiON cantilever edge coupler used for wafer level, automated probing of InP devices, and in (h), a top-down experimental image with SiON probe on the left and InP waveguides on the right, after passive assembly173 (©2021 X. Leijtens et al., licensed under CC BY 4.0)
