High-Density 2$\,\times\,$4 Channel Polymer Optical Waveguide With Graded-Index Circular Cores

We propose to introduce a densely aligned 2times4 channel polymer parallel optical waveguide with graded-index circular cores for board-level optical interconnection, which is fabricated using the preform method. It is verified that this novel waveguide has sufficiently low loss (0.028 dB/cm at 850 nm and 0.061 dB/cm at 980 nm) and high bandwidth, due to the specific characteristic of the graded-index profile. This paper discusses insertion loss sensitivity to the displacement of the launched beam, various inter-channel crosstalk properties, and inter-channel skew, taking into account the real implementation of waveguides on printed circuit boards, especially for high-speed optical interconnects.