Investigation on mode dispersion and lamination stability of multimode polymer waveguides for an optical backplane

In this paper, two noteworthy issues of mode dispersion and lamination stability of multimode polymer waveguides for optical backplane are investigated. In the case of center launching by 50-µm graded-index (GI) multimode fiber (MMF), mode dispersion of polymer waveguides with different widths is analyzed theoretically and measured in the view of bit error rate (BER) curves. Compared with the waveguide with the width of 40 µm, 1-dB power penalty is observed by the 70-µm-width waveguide due to its larger mode dispersion. On the other hand, waveguide stability after laminating process with high temperature and pressure is measured experimentally. No significant changes in core shape and size are observed. The average insertion loss of 80 channels before and after lamination are 0.137 dB/cm and 0.192 dB/cm, respectively. Error-free transmission at 25 Gb/s is obtained by laminated waveguides. The results imply the feasibility and potential of multimode waveguides for optical backplane.