Next-gen 100 Gigabit short reach optics starts to take shape

The latest options for 100 Gigabit-per-second (Gbps) interfaces are beginning to take shape following a meeting of the IEEE 802.3 Next Generation 100Gb/s Optical Ethernet Study Group in November. 

The interface options being discussed include: 

• A parallel multi-mode fibre using a VCSEL with a reach of 50m to 70m. An active optical cable version with a 30m reach, limited by the desired cable length rather than the technology, using silicon photonics or a VCSEL has also been proposed.

• A parallel single-mode fibre using a 1310nm electro-absorption modulated laser (EML) or silicon photonics with a range of 50m to 1000m+.

• A duplex single-mode fiber, using wavelength division multiplexing (WDM) or pulse-width modulation (PAM), an EML or silicon photonics for a 2km reach.

“I think in the end all will be adopted,” says Marek Tlalka, director of marketing at Luxtera. "Users will be able to choose what is most economical."

Jon Anderson, director of technology programme at Opnext, stresses however that these are proposals.

"No decisions were reached by the Study Group on any of these proposals," he says. “The Study Group is only working towards defining objectives for a next-gen 100 Gigabit Ethernet Optics project.” Agreement on technical solutions is outside the scope of the Study Group.

Anderson says there is a general agreement to define a 4x25Gbps multi-mode fibre optical interface. But the issues of reach and multi-mode fibre type (OM3, OM4) are still being studied.

“The Study Group has not reached any agreement on whether a 100GE short reach single-mode objective should be pursued," says Anderson. “Discussion at this point are on reach, power consumption and relative cost of possible solutions with respect to (the 10km) 100GBASE-LR4."