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High Speed Optical Fiber Transceiver Promote the Development of Optical Engine

Author: SOPTO

7/8/2013, mature plug in package of 10Gbps XFP transceiver is also in continuing evolution. Trans-mode integrates its system with tunable laser based on XFP, and said tunable XFP has important advantage. Menara Networks then conversely integrate system function to XFP which is usually used for on line card XFP only.

 

Up to now, the deployment of fixed wavelength DWDM XFP means that system suppliers must have considerable inventory in case operators deploy new DWDM wavelength. Ferej said, if there is no inventory, system suppliers must wait until customer confirm the wavelength, then they can make transceiver order to the supplier, this means 12-18 weeks delivery time. But using tunable XFP, one transceiver can meet the requirements of all wavelength planning operators.

 

In addition, the optical properties of XFP are only slight inferior to that of 10 Gbps 300 pin SFF MSA, the latter only has the advantage of 2-3dB optical signal-to-noise ratio. That means it needs longer achievable rate to make signal passing through more optical amplifier. Using 300 pin packages can increase total rate of accessibility in situation of repeater cases not available outside of 1000km.

 

CFP is suitable for data center, but high density applications of linking switch and high performance computing require more compact design, for example, QSFP, CXP as well as so-called optical engine.

 

Fiber Optic Module

 

QSFP is interface favored by active cable, also one reserved alternative of copper interconnects. QSFP transceiver supports quadrupling data rate (QDR) 4xInfiniband, can extend 4x10 Gbps Ethernet rate accessibility of copper outside of 7m. It is also one options of more compact 40 GbE short distance interface.

 

It’s also a problem to realize 100 GbE in QSFP, because how to meet the power limit of QSFP, but at the same time to add a 25 Gbps channel interface and several high speed lasers is quite a headache problem, which may requires an intermediate level package definition.

 

CXP is a kind of front panel interface that can realize more intensive interface in data center, and it is particularly useful for chassis link. According to Avago Technologies introduction, Infiniband is the first target market for CXP, but before CXP connector can be used in 100 GbE Ethernet, there needs to solve a number of technical problems, such as fulfilling requirements of optical IEEE specifications.

 

To optical engine, for example, SNAP12 parallel optical module can be used to connect several platforms in large IP router configuration, as well as for high-end computing. This module is not plug-in package, but consisted of independent12 channel transmitter and receiver modules, with 6.25 Gbps channel data rate.

 

CXP and SNAP12 each have their own advantages, for example, SNAP12 is located on motherboard and its small package makes it able to be set in the side of ASIC. For those companies that use optical engine to reduce the cost of parallel interface and meet the requirement of high speed interface between motherboard and frame and among systems, this kind of method is very suitable.

 

The arrival of 100 GbE and higher rate times, and 25 Gbps electric interface will further promote the development of optical engine. But it is very difficult to route 10 Gbps in normal FR4 printed circuit board, therefore, for longer link (maximum 10 inches), we need to use techniques of pre emphasis, electronic dispersion compensation and retiming.

 

Fiber optic transceivers are probably in public attention center of dealing with network flow, but links platform, panel and board equipment and etc are the space that optical fiber transceiver supplier can play to achieve product differentiation.

 
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