Issue link: https://www.epageflip.net/i/1043933
32 I ICT TODAY Active Optical Cables Active optical cables, as shown in Figure 2, are used in limited range interconnect applications in data centers. For high-speed links at 40 Gigabit Ethernet (GbE) and 100 GbE, this means using multiple lanes of data over ribbon cables. Ribbon cables also facilitate mass fusion splicing that can splice up to twelve fibers at a time, thereby saving time and labor cost dollars. At 10 GbE or 25 GbE, a single lane or optical fiber per direction is enough. An AOC is often based on multimode optical fibers while some (e.g., parallel singlemode 4) is on singlemode optical fiber. A key attribute is that AOC employs the same connectors as pluggable optics and performs electrical-to-optical conversions at each cable end. In practice, this means quad small form-factor pluggable (QSFP) terminations for 40 GbE and 100 GbE and small form-factor pluggable (SFP) terminations for 10 GbE and 25 GbE. The AOC is therefore active and includes transceiv- ers, control chips and modules, in addition to the fiber optic cable. AOC cables are of fixed length, starting at just a few meters (m) with possibilities up to 100 m or more. Technically, an AOC does not have to comply with an Ethernet interface type although many advertise a certain type in their coded information. Table 1 provides a list of potential Ethernet interface types. In the table, RS-FEC refers to the Reed-Solomon FIGURE 2: AOC cable. TABLE 1: Potential Ethernet interface types. CWDM4 MSA 2 km SMF 4 λ / dir 1310 nm Yes QSFP28 CLR4 Alliance 2 km SMF 4 λ / dir 1310 nm Optional QSFP28 PSM4 MSA 500 m SMF 4 fibers / dir 1310 nm Yes QSFP28 SWDM4 Alliance 75 m 100 m 150 m OM3 MMF OM4 MMF OM5 MMF 4 λ / dir 850 nm Yes QSFP28 100GBASE- SR4 70 m 100 m OM3 MMF OM4 MMF 4 fibers / dir 850 nm Yes QSFP28 100GBASE CR4 5 m Twinaxial 4 cables / dir N/A Yes QSFP28 SWDM4 Alliance 240 m 350 m 440 m OM3 MMF OM4 MMF OM5 MMF 4 λ / dir 850 nm No QSFP+ 40GBASE-SR4 100 m 150 m OM3 MMF OM4 MMF 4 fibers / dir 850 nm No QSFP+ 40GBASE CR4 7 m Twinaxial 4 cables / dir N/A No QSFP+ 25GBASE-SR 70 m 100 m OM3 MMF OM4 MMF 1 fiber / dir 850 nm Yes SFP28 25GBASE CR 5 m Twinaxial 1 cable/ dir N/A Yes SFP28 25GBASE CR-S 3 m Twinaxial 1 cable / dir N/A No SFP28 10GBASE-SR 33 m 400 m 62.5 µm MMF 50 µm MMF 1 fiber / dir 850 nm No SFP+ 10GBASE- CR 15 m Twinaxial 1 cable / dir N/A No SFP+ Ethernet Rate Interface Type Maximum Reach Medium No. of fibers/ wavelengths Wavelength Range RS-FEC Pluggable Type 100 GbE 40 GbE 25 GbE 10 GbE