Design and fabrication of large fiber-mode-matched three-dimensional adiabatic tapered couplers for integrated optics

We presented the design and fabrication of fiber-mode-matched three-dimension (3D) tapered couplers for efficient coupling light from fibers to photonic integrated circuits (PICs). The 3D adiabatic taper was made by SU8 and the structure was designed by beam propagation method (BPM). Measuring waveguide transmission with this 3D taper, we observed that the coupling efficiency was improved by 12 dB. The misalignment tolerance can be around 5 μm.