Tag Archives: optical transceivers

Next Generation Of 40G CFP Module

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In fibre optic communication, the industry has long decided the SFP+ (Small Form-factor Pluggable) at 10Gbps while the 40GBASE QSFP+ (quad small-form-factor pluggable) has become the 40Gbps form factor of choice. With 100Gbps still in its infancy, transceiver vendors are pursuing several client-side interfaces. Much work will be needed to reduce the size, power consumption and cost of 100Gbps interfaces before the industry settles on a single pluggable form factor for the single mode and multimode standards. This article will introduce CFP module.

CFP module

CFP module (C form-factor pluggable) is a Multi-Source Agreement (MSA) that defines a hot-pluggable optical transceiver form factor to enable 40 Gb/s and 100 Gb/s applications, including next-generation High Speed Ethernet (40 GbE and 100 GbE). Pluggable CFP transceivers will support the ultrahigh bandwidth requirements of data communications and telecommunication networks that form the backbone of the Internet. The CFP transceiver features twelve transmit and twelve receive 10Gb/s lanes to support one 100GbE port, or up to three 40GbE ports. Its larger size is suitable for the needs of single-mode optics and can easily serve multimode optics or copper as well.

CFP Module Compared With CXP And QSFP

The CXP transceiver form factor also provides twelve lanes in each direction but is much smaller than the CFP and serves the needs of multimode optics and copper.

The QSFP+ Module is similar in size to the CXP and provides four transmit and four receive lanes to support 40GbE applications for multimode fibre and copper today and may serve single-mode in the future. Another future role for the QSFP may be to serve 100GE when lane rates increase to 25Gb/s.

The Develop Trends Of Next Generation CFP Module

The current generation of modules are large because of heat dissipation issues due to high power consumption. For example, the CFP is rated for up to 24 watts of power dissipation but also needs to have a range of high density electrical connectors to connect to the baseboard. I take this to mean big, hot and heavy.

With the completion of 40/100 Gigabit Ethernet (GbE) optical interface standards (IEEE 802.3ba-2010) and pluggable optical transceiver module specifications, and with the production shipment of first-generation 40GbE/100GbE CFP products underway, optical module vendors are focusing on developing technologies and proving design-ins for their next-generation 40/100GbE pluggable optical transceivers.

The purpose of the CFP MSA is to define a hot-pluggable optical transceiver form factor to enable 40-Gbps and 100-Gbps applications, including next-generation High Speed Ethernet (40 Gigabit Ethernet and 100 Gigabit Ethernet). The pluggable CFP transceivers are designed to support the ultra-high bandwidth requirements of data communications and telecommunications networks.

The key objectives of next-gerneration of CFP modules include significant reductions in module power dissipation and size, which are critical to increasing system port density and reducing overall optical port cost for system vendors and their customers. Critical technologies for tackling these design targets include 4x10G and 4x28G hybrid integrated TOSAs/ROSAs and process improvements in 28G gearbox and CDR ICs. There also may be consideration of uncooled CWDM 28G laser technology for realizing 100GbE optical transceivers in a QSFP+ like form factor for short singlemode fibre.

FS.COM developed the 40GbE CFP module for 10km transmission by using a high-speed four-wavelength CWDM laser diode, through the application of its own low-power-consumption drive technology and high-density mounting technology. Moreover, you can find other 10G, 40G fibre optic transceivers at this website.

High-speed Fibre Optical Transceiver Promoting The Development Of Optical Engine

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Mature plug-in package transeivers like 10Gbps XFP transceivers continue to evolve. Transmode in its system integrated XFP-based tunable lasers, called tunable XFP which has important advantages. Opposite to the Menara Networks, integrated the system function to XFP commonly only for line card.

XFP With New Uses

Until now, the deployment of fixed wavelength DWDM XFP means that the system supplier must possess considerable amount of inventory to prepare for operators to deploy new DWDM wavelengths needed.

If there is no inventory, system vendors must order transceivers to the supplier only after waiting for customers to confirm the wavelength, which implies the delivery period of 12-18 weeks. While the use of tunable XFP, just a transceiver can meet the wavelength planning requirements for all operators.

In addition, the optical property of XFP is only slightly after 10 Gbps 300-pin SFF MSA, which only has “2-3dB optical signal-to-noise ratio advantage, means the need for a longer rate to make signal through more optical amplifiers”. Increasing the total achievable rate using the 300 pin packages are available in the 1000km without the use of repeaters.

MSA power and space specifications (such as XFP) are important for component supplier?

It appears important only in a demand. For example, the maximum rated power of XFP is 3.5W, if you use a tunable XFP, a thermoelectric cooler is occupied 1.5-2W, lasers occupy 0.5W, TIA occupied a part, then left to the modulator driver there is not much left.

At the same time, Menara Networks has implemented the optical transmission network (OTN) of ITU-T in the XFP application in the form of specific integrated circuit (ASIC). OTN used in adding optical performance monitoring function and transmitting error correction, at the same time, for signal transmission package. Through the integration of OTN in the plug-in package, package, the functions of signal package, achievable rate and optical signal management can be added to the IP routers and carrier Ethernet switch routers. This design has several advantages: the elimination of the needs of using additional 10 Gbps transponder to transmit switch or router signal (for DWDM transmission), and allows system suppliers to develop universal card without support OTN. But the biggest technical problem for Menara is the development of the included software rather than the development of OTN ASIC.

Plug-in type and Optical Engine

CFP is applicable to the data centre, but the high density applications such as link switch and high performance computing require a more compact design, such as QSFP, CXP and the so-called optical engine.

QSFP is favored interface by the active cable, also is one of the alternative options for copper interconnects. The QSFP transceiver support Quad Data Rate (QDR) 4xInfiniband, can extend the copper cable 4×10 Gbps Ethernet achievable rate of outside 7m. It is also one of the options for more compact 40 GbE short distance interface.

Achieving 100 GbE in QSFP is also a problem, because how to meet the QSFP power limits while adding a 25 Gbps / channel interface and a number of high-speed lasers is quite a headache problem, may need a intermediate package of level definition.

While CXP is a front panel interface can realize more intensive interface in the data centre, is particularly useful for the links between chassis. According to Avago Technologies, the Infiniband is the first target market for CXP, but before CXP transceiver applied in the 100 GbE Ethernet there are several technical problems need to solve, for example, to meet the requirements of IEEE optical specifications.

For optical engine, for example, SNAP12 parallel optical module can be used to connect a plurality of platforms of large-scale IP router configurations, as well as for high-end computing. However, this module is not a plug-in package, is composed of 12 independent channel transmitter and receiver modules, with 6.25 Gbps / channel data rate.

CXP and SNAP12 own self-advantages, such as SNAP12 located on the motherboard and its small package makes it possible to set up next to the ASIC. For those who use optical engine to reduce the cost of parallel interface and meet the requirement of high-speed interface between the motherboard, frame and system, this kind of method just fits its meaning.

100 GbE as well as the arrival of more high-speed era, plus 25 Gbps electric interface will further promote the development of optical engine. But in the standard FR4 printed circuit board to route 10 Gbps is very difficult, and longer link (up to 10 inches) need to use pre-emphasis, electronic dispersion compensation and retiming techniques.

Fibre optic transceivers may be deal with the surge network traffic, but the functions like link platforms, panels and board equipments are the play space where fibre optical transceiver supplier can achieve product differentiation.