Rosenberger Optical Solutions & Infrastructure (Rosenberger OSI), manufacturer of innovative fibre optic cabling infrastructures in Europe, is now also introducing 8° APC angled polished multimode connectors into its successful PreCONNECT® OCTO and DUODECIM MTP® cabling system. Due to this angled polish, the return loss is significantly increased and remains stable high during operation, explains Harald Jungbäck, product manager for data centre cabling systems at Rosenberger OSI.
APC 8° angled polish at multimode MTP® connectors already proven at PreCONNECT® SEDECIM
For this launch, the cabling specialist is utilising the APC 8° angled polishing on multimode MTP® connectors, which was first introduced to the global market in May 2020 in conjunction with PreCONNECT® SEDECIM. The APC 8° bevel has been employed on single-mode MTP®/MPO connector end faces from the inception of MTP®/MPO technology, with the objective of attaining a stable, high return loss. In contrast, prior to May 2020, only the PC° 0 straight cut was employed for multimode MTP®/MPO connector end faces.
The PC° 0° straight polish design has the potential to cause performance issues in multimode MTP®/MPO connectors due to the presence of dirt particles. In the past this has often led to low return loss values. This problem has become increasingly pronounced in recent years, coinciding with a notable surge in application data rates. The introduction of reflection-sensitive PAM4 coding at 400GBASE-SR8 and other multimode applications with serial lane speeds of 50 Gbit/s has further highlighted the severity of this issue.
Reasons for the introduction of APC 8° angled polish at multimode MTP® connectors
When 400GBASE-SR8 was introduced to one of the world's largest hyperscalers in 2019, these problems were severe enough that Rosenberger OSI was compelled to revisit the research results on the APC 8° angled polish on multimode MTP®/MPO ferrule endfaces thar had been collected in 2012. The results demonstrate that Multimode MTP®/MPO connectors with APC 8° angled polish provide a consistently high return loss in the specified application, in comparison to those with PC 0° straight polish.
Based on the clear facts of these tests, the hyperscaler, also in close cooperation with the MTP® inventor and manufacturer US Conec, decided to specify the multimode MTP®/MPO 16 ferrule endfaces APC 8°. This decision not only affected the cabling infrastructure but also the 400GBASE-SR8 Transceiver Media Dependent Interface (MDI).
These findings and several years of experience have led to the further development of the APC 8° angled polish in the upcoming multimode 400GBASE-SR4 OCTO (4+4) transceivers. “This means that it is now time to offer APC 8° angled polished multimode OCTO (4+4) and DUODECIM (12) MTP® connectors as an alternative to the PC 0° polished multimode MTP® connectors of our PreCONNECT® OCTO (4+4) and DUODECIM (12) multimode, which can still be ordered”, says Jungbäck. As with PreCONNECT® SEDECIM, the APC 8° polished multimode OCTO (4+4) and DUODECIM (12) MTP® connector can be recognized by its white boot on the black connector. OCTO (4+4) and DUODECIM (12) MTP® connectors and their corresponding couplers have centred keys, SEDECIM (16) off-centre keys.