Update on Fiber Optic Connectors: Very Small Form Factor connectors are on the rise


Fiber-optic connectors are important components that permit higher port densities

Fiber-optic cables can be assembled with a variety of plug connectors. They are vital components that ensure the performance and reliability of the passive infrastructure. They are also important because they help save space in data centers by permitting higher port densities. Alongside conventional plug connectors such as, for example, LC, SC and MU connectors, the new VSFF plug connectors are currently on the rise. You can find out more about the conventional plug connectors here. The current blog article focuses on the CS®, SN® and MDC Very Small Form Factor (VSFF) connectors. 


VSFF connectors: Different types and port densities

The VSFF connectors have a very small form factor, underlining the fact that fiber-optic connectors have developed to become extremely compact, space-saving connector types. They have a modular design in the form of duplex connectors and can be combined to create multiple connectors. The aim is to further increase the port density in data centers. We present the three most common VSFF plug connectors: CS®, SN® and MDC.


CS® Connector

The CS® connector was one of the first VSFF connectors to become available on the market. The CS® EZ-Flip connector’s unique, push-pull tab ensures ease of handling at a high packing density. The plug connector is able to accommodate up to 2.0/3.0 mm duplex fibers. It was taken over by QSFP-DD (Quad Small Form Factor Pluggable Double Density), OSFP (Octal Small Form Factor Pluggable) and COBO (Consortium for On-Board Optics) and standardized by the TIA (Telecommunications Industry Association). Using the CS® plug connector, it is possible to double the port density in panels when compared to the LC-Duplex connector. The connector is primarily used for long-distance transceivers.


SN® Connector

The SN® connector from Senko is another VSFF connector. It is based on 1.25 mm fully-ceramic ferrule technology. The SN® EZ-Flip variant makes it possible to change the polarity on-site without having to interrupt the fibers or reposition the ferrules. It is not only possible to change the polarity in the PC variant. Thanks to the unique alignment of the angled ferrules, it is also possible to reverse the polarity of APC connectors. The SN® connector was developed for OSFP/QSFP-DD breakout applications.


MDC Connector

The MDC (which stands for Miniature Duplex Connector) from US Conec also belongs to the VSFF category and is a genuine push-pull duplex plug connector. It is also manufactured on the basis of 1.25 mm fully-ceramic ferrule technology. Developed as a Media Dependent Interface (MDI) or Optical Interface for the new SFP-DD and QSFP-DD transceivers, it also has the potential to replace the LC-Duplex mass-use connector.


VSFF connectors offer higher port densities than conventional connectors

Due to their size and depending on the coupling configuration, VSFF connectors offer higher port densities in 19” distribution panels. A sensible choice with MDC and SN® is a maximum port density of 128 ports per height unit in a 19” distribution panel because this can still be patched without additional tools using just your fingers. By contrast, “only” 96 ports per height unit (SMAP-G2 UHD) are possible using LC-Duplex connectors. 


PreCONNECT® OCTO SN® application Port-Breakout

400Gbit/s to 4 x 100Gbit/s

Patchcord SN®

PreCONNECT® OCTO SN® Breakout-Trunk

Patchcord SN® - LCC PPB


PreCONNECT® OCTO MDC application Port-Breakout

400Gbit/s to 4 x 100Gbit/s

Patchcord MDC

PreCONNECT® OCTO MDC Breakout-Trunk

Patchcord MDC - LCC PPB


Harald Jungbäck, Product Manager FO cabling systems

Harald Jungbäck draws his fiber optic expertise from his many years of work at Rosenberger OSI. In 1993 he started his career in product and manufacturing process development. Today he is responsible for the consistent expansion of the product range and the technological innovation process in this area.