In developing the PreCONNECT® SEDECIM, which is optimized for 400GBASE-SR8 transmission technology, the cabling specialist utilizes a technology already proven effective in single-mode applications. The 8° APC angle polish is used from the outset for single-mode MTP®/MPO ferrule terminations to achieve reliable return loss. In contrast, only the 0° PC straight polish was previously used for multi-mode MTP®/MPO ferrule terminations.
Due to their PC° 0° straight-polished design, MTP®/MPO multimode connectors were particularly susceptible to performance issues caused by dirt particles, which in the past often led to unreliable return loss values. In recent years, this problem has become increasingly serious due to the sharp increase in application data rates. The introduction of reflection-sensitive PAM4 encoding in 400GBASE-SR8 and other multimode applications with serial speeds of 50 Gbit/s has demonstrated its full potential.
"When 400GBASE-SR8 was introduced at one of the world's largest hyperscalers in 2019, these problems were so severe that the results of Rosenberger OSI's 2012 research on 8° APC angle polishing of MTP®/MPO multimode ferrule ends were already being used. Measurements demonstrate that MTP®/MPO multimode connectors with 8° APC angle polishing, in contrast to those with 0° PC direct polishing, guarantee high and reliable return loss in the application. Based on the clear findings of these tests, the hyperscaler, also in close collaboration with the inventor and manufacturer of MTP®, USCONEC, decided to specify 16 APC 8° MTP®/MPO multimode ferrule terminations. This decision affected not only the cabling infrastructure but also the 400GBASE-SR8 Media Dependent Interface (MDI) transceiver. There was also no discussion on this matter regarding our SEDECIM." “PreCONNECT®,” says Jungbäck. Therefore, 400GBASE-SR8 transceivers can now have either a PC MTP®/MPO 16 0° or an MTP®/MPO 16 APC 8° media interface. The distinguishing feature of the innovative MTP®/MPO multimode connector system, with 16 fibers in a row and an APC 8° angle polish, is a white folding protective sleeve on the black connector.
