Advantages and application of high-speed optical interconnection

6/11/15  |  Technical Article

Data center / cloud computing system needs higher bandwidth and lower power consumption and more urgent, AOC is one of the best solutions to meet this demand. AOC (active optical cables) compared with the copper interconnect has many significant advantages, such as lower on the system link transmission power, weighs only a quarter of direct-attached copper, copper-half volume slightly, and room cabling system has better air flow heat dissipation than copper cable bend radius can be made smaller, over longer distances (up to 100 to 300 meters), and the error rate is also better transmission performance , BER can reach 10 ^ -15. Compared with the optical transceiver module, AOC is not exposed due to the presence of optical interface, optical interface clean and contaminated problem does not exist, the system greatly enhanced stability and reliability, and reduce maintenance costs the engine room.

High-speed optical interconnect products 40Gbps QSFP+ AOC and 120Gbps CXP AOC no longer adopt the traditional pluggable transceiver design TOSA / ROSA, and the use of highly integrated array light engine core device technology. 

On PCBA using COB (Chip on Board) integrated technology, integrated model - small package, high speed, low power consumption (QSFP+ consumes less than 1.5W, CXP consumes less than 2.5W). On the transmit side, the array of optical engine to handle multiple high-speed electrical channels, convert it to a multi-channel optical signal, and then the optical signals are combined (24 cores) MPO high-density optical cable will transmit this information via a 12-pin to the next node cloud computing system or data center room. At the receiving end, the array optical engine will MPO optical signal is converted back to electrical signals within the cable will be dealing with multiple signals transmitted to the device. These products are fully applicable infiniband Internet application scenarios, consistent with Ethernet IEEE 802.3ba. In the data center and cloud computing systems in the field, an array of optical engine technology has been widely applied to an active cable products - interconnection between servers and switches.

But optical engine technology is also facing great challenges, the core of the laser is monopolized by a few large international companies, expensive, and welding technology between the driver and limiting amplifier chip made of laser also affects the efficiency of domestic companies to significantly restricts promotion. For these reasons, the Integration of silicon photonics technology is the future development trend of optical interconnection technology --- the entire optical engine integrated on silicon platform that integrates all the necessary functions to achieve lower cost, easier made technology, and establish higher density optical transmission systems.

In the data center room, offers a variety of high-speed optical communications port equipment (servers, switches and HBA, etc.) need to be connected by a cable together to work. So how to solve the interconnect any two devices do? Such as 10G SFP+ and 40G QSFP+ equipment. QSFP+ active optical cable transfer four SFP+ AOC optical interconnection products as the best solution to achieve QSFP+ and SFP+ devices are interconnected.

QSFP+ turn 4 * SFP+ high speed active cable products, one end is 40Gbps QSFP+ interface, the other end has four 10Gbps SFP+ interface through the middle 12 core MPO high-density fiber optic cable, then according to customer demand for both ends of the cable length in MPO cable splitter to join the middle, all the way to achieve 40G optical signal into four 10G signals. One end of the cable using the 40G QSFP connectors meet the requirements of SFF-8436; the other end 4-way 10G SFP+ connectors meet the requirements of SFF-8432, is the most economical implementation of simple switch port switching. Transmission length up to 1 to 100 meters, both ends of the splitter to the cable length can be freely selected. Similarly, 120G CXP turn three 40G QSFP+ interconnect products can solve CXP and QSFP equipment interconnection problems, need to be raised through the middle 24 core high-density MPO fanout three 4-core cable products, complete perfect transfer.

Significant advantages of optical interconnects data centers to become integrators, equipment manufacturers focus of attention. Large-scale deployment of optical interconnection products will become a common global trend of large data, high-density, high-capacity data centers and cloud computing.