CFP CFP2 CFP4 CFP8 Transceiver Module

The CFP Multi-Source Agreement (MSA) defines hot-pluggable optical transceiver form factors to enable 40Gb/s and 100Gb/s applications, including next-generation High Speed Ethernet (40GbE and 100GbE). Pluggable CFP, CFP2 and CFP4 transceivers will support the ultra-high bandwidth requirements of data communications and telecommunication networks that form the backbone of the internet.

The first-generation 100GBase-LR4/ER4 optical transceiver architecture is similar to that of the 40GBase-LR4, but with the speed of the active optoelectronic components increased to 28Gbps for realizing a 4x28G optical interface. Additionally, the CAUI electrical interface defined in IEEE 802.3ba-2010 is widened from 4x10G lanes to 10x10G lanes. A 10:4/4:10 “gearbox” serializer/deserializer IC is used to implement the electrical interface between the 10-lane host data path and the four-lane optical data path.

The optical interface defined in IEEE 802.3ba-2010 uses a four-wavelength LAN-WDM 800-GHz wavelength grid in the 1310-nm band and optical multiplexing/de-multiplexing on single mode fiber. The transmitter optical specifications for LR4 and ER4 are based on cooled electro-absorption modulation with integrated DFB (EA-DFB) laser technology, but were written to allow eventual implementation with directly modulated DFB lasers for smaller size, lower power consumption, and lower cost TOSAs.

The receiver optical specifications for LR4 and ER4 are based upon PIN-PD detector technology with integrated TIA. The receiver specification also includes optical amplification, such as from a semiconductor optical amplifier, to compensate for optical fiber attenuation loss in the ER4 40-km application.

These components are packaged into the CFP pluggable module (previously shown in figure 1) with non-coaxial, 28-Gbps electrical connections between the discrete component TOSAs, ROSAs, and gearbox IC, as shown in figure 2 below.

The first-generation 100Gbase-LR4 module power dissipation is typically in the range of 24 W, which poses significant thermal management challenges for system designers, particularly as they seed to increase 100GbE optical port density. Thus, there is strong motivation to significantly reduce the 100GBase-LR4 optical transceiver module power dissipation in the next-generation design.