Optical transmission's era of rapid capacity growth

Kim Roberts, senior director coherent systems at Ciena, moves from theory to practice with a discussion of practical optical transmission systems supporting 100Gbps, and in future, 400 Gigabit and 1 Terabit line rates. This discussion is based on a talk Roberts gave at the Layer123's Terabit Optical and Data Networking conference held in Cannes recently. 

Part 2: Commercial systems

The industry is experiencing a period of rapid growth in optical transmission capacity. The years 1995 till 2006 were marked by a gradual increase in system capacity with the move to 10 Gigabit-per-second (Gbps) wavelengths.  But the pace picked up with the advent of first 40Gbps direct detection and then coherent transmission, as shown by the red curve in the chart. 

Source: Ciena

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The capacity limits facing optical networking

Ever wondered just how close systems vendors are in approaching the limits of fibre capacity in optical networks? Kim Roberts, senior director coherent systems at Ciena, adds some mathematical rigour with his explanation of Shannon's bound, from a workshop he gave at the recent Layer123's Terabit Optical and Data Networking conference held in Cannes. 

Part 1 Shannon's bound

 Source: Ciena

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FPGA transceiver speed hikes bring optics to the fore

Despite rapid increases in the transceiver speeds of field-programmable gate arrays (FPGA), the transition to optical has begun.

FPGA vendors Xilinx and Altera have increased their on-chip transceiver speeds four-fold since 2005, from 6.5Gbps to 28Gbps. But signal integrity issues and the rapid decline in reach associated with higher speed means optics is becoming a relevant option.

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The CFP4 optical module to enable Terabit blades

The next-generation CFP modules - the CFP2 and CFP4 - promise to double and double again the number of 100 Gigabit-per-second (Gbps) optical module interfaces on a blade.

Using the CFP4, up to 16, 100Gbps modules will fit on a blade, a total line rate of 1.6 Terabits-per-second (Tbps). With a goal of a 60W total module power budget per blade, that equates to 27Gbps/W. In comparison, the power-efficient SFP+ achieves 10Gbps/W.

 

Source: Gazettabyte, Xilinx

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The great data rate-reach-capacity tradeoff

Source: Gazettabyte

Optical transmission technology is starting to bump into fundamental limits, resulting in a three-way tradeoff between data rate, reach and channel bandwidth.

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Plotting transceiver shipments versus traffic growth

Chart Watch: LightCounting

Summing transceiver shipments in the core of the network and plotting the data against traffic growth provides useful insights into the state of the network.

"We use transceiver shipment data [from vendors] to calculate how fast the network is growing and compare it to the traffic growth," says Vladimir Kozlov, CEO of market research firm, LightCounting.

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Optical components: The six billion dollar industry

Chart Watch: Ovum Components

The service provider industry, including wireless and wireline players, is up 6% year-on-year (2Q10 to 1Q11) to reach US $1.82 trillion, according to Ovum. The equipment market, mainly telecom vendors but also the likes of Brocade, has also shown strong growth - up 15% - to reach revenues of over $41.4 billion. But the most striking growth has occurred in the optical components market, up 28%, to achieve revenues of over $6 billion, says the market research firm.

Source: Ovum

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