Design and fabrication of vertically coupled curved waveguides for 3D optical interconnection and photonic integrated circuit application

초록

We demonstrate for the first time a novel optical interconnection structure that we have named vertically coupled curved waveguides which can be used to optically interconnect light sources like VCSELs and PDs in the form of photonic integrated circuits. It consists of 4-channel polymer waveguides of 5um height x 5um width x 5cm length. The waveguides have tapered structure with 120um width and is vertically curved up at each end of the waveguide. The radius of the curved waveguide is 600um and can be simply defined by optical lithography technique. Large misalignment tolerance has been achieved. The dimension of the waveguide is 120x120um at each end. UV embossing technique is used for fabrication. Two molds for replicating upper-cladding and under-cladding are used. Replicated claddings are bonded by core material polymerization. Transmission characteristics of the fabricated waveguides were measured using a 4x1 VCSEL and PD arrays and the data rate was measured up to 2.5Gbps for each channel waveguide. We found that this new structure is an alternative approach for allowing vertical interconnection to other methods using 45-degree mirrors or prisms. There is a possibility that this structure can be applicable to the photonic integrated circuits leading to optical printed circuit board (OPCB) in 3-dimensional structure.