New-Tech Europe | April 2018

and 10km typical reaches. With each increase in distance, the costs of the technology and manufacturing rises exponentially. For example, a 10km single-mode transceiver may cost 10-15 times that of a 100m multi- mode transceiver as it is considerably costlier to build. Going Forward While 25G signaling enabling 50G (2x25G) and 100G (4x25G) cables and transceivers, switches and adapters has now hit the mainstream, Mellanox has 200G technologies on the launch pad using the new signaling modulation called PAM4 or Pulse Amplitude Modulation 4-levels. PAM4 keeps the same 25G clocking so the electrical infrastructure can minimize its costs but doubles the net data rate by sending 2-bits per clock. Called 50G PAM4 Mellanox will be offering 4-channel devices supporting 200G links and soon 8-channel switches, network adapters, cables and transceivers offering 400G per link. Summary Data center server racks have been called the 4-th industrial revolution’s equivalent of the steam engine and all associated technologies are advancing at an incredible rate. In the span of just a few years, the industry has gone from 1G/10G to 200G/400G interconnects. What used to constitute the total yearly unit volumes for a market segment including all suppliers can now be found in a single order from a single hyperscale buyer! All this advanced technology is poised to change our world in ways never conceived. Author Brad Smith, Director of Marketing, LinkX Interconnects, Mellanox Technologies DAC, AOCs, Optical Transceivers, Ethernet & InfiniBand Networking

image3: Mellanox LinkX DAC, AOC Cables and Optical Transceivers

to be disconnected from the optical fiber, connectorized transceivers are used. These are available in two basic technologies based on the fiber core diameter and optical window of the fiber and wavelength of the lasers. Multi-mode: Large 50-um fiber core using 850nm wavelength vertical cavity lasers (VCSELs) Single-mode: Tiny, 9-um fiber core using 1310nm wavelength edge emitting lasers (DFB, DML, EMLs etc.) While multi-mode transceivers are easy to assemble and low cost due to the large core diameter, the signal typically degrades significantly after 100 meters with 25G and 50G signaling. For longer reaches, different single-mode technologies are used, and cost optimized for 500m, 2km,

meters after which physical installation starts to become an issue favoring connectorized optics. AOCs are the least expensive optical link available and since the optics is all contained inside the cable assembly, it acts as like a DAC a plug & play cable. Mellanox 100G QSFP28 AOCs consume about 2.2 Watts, one of the lowest power consumption ratings in the industry. Mellanox achieves this by not only designing the entire AOC transceiver end but also the integrated circuits used to drive the laser and detector inside called TIA/LD. This enables Mellanox to optimize the power and signal integrity of the cable assembly. Optical Transceivers Where the optical transceiver needs

Image 4: Mellanox Network Switches, Adapters, Cables and Transceiver Including Wafer ICs Display at OFC 2018

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