MultiPhy targets low-power coherent metro chip for 2013

MultiPhy has given first details of its planned 100 Gigabit coherent chip for metro networks. The Israeli fabless start-up expects to have samples of the device in 2013. 

"We can tolerate greater [signal] impairments which means the requirements on the components we can use are more relaxed"

Avi Shabtai, CEO of MultiPhy

"Coherent metro is always something we have pushed," says Avi Shabtai, CEO of MultiPhy. Now, the company says it is starting to see a requirement for coherent technology's deployment in the metro. "Everyone expects to see it [coherent metro] in the next 2-3 years," he says. "Not tomorrow; it will take time to develop a solution to hit the target-specific [metro] market."

MultiPhy is at an advanced stage in the design of its coherent metro chip, dubbed the MP2100C. "It is going to be a very low power device," says Shabtai. MultiPhy is not quoting target figures but in an interview with the company's CTO, Dan Sadot, a figure of 15W was mentioned. The goal is to fit the design within a 24W CFP. This is a third of the power consumed by long-haul coherent solutions.

The design is being tackled from scratch. One way the start-up plans to reduce the power consumption is to use a one-sample-per-symbol data rate combined with the maximum-likelihood sequence estimation (MLSE) algorithm. 

MultiPhy has developed patents that involve sub-Nyquist sampling. This allows the analogue-to-digital converters and the digital signal processor to operate at half the sampling rate, saving power. To use sub-Nyquist sampling, a low-pass anti-aliasing filter is applied but this harms the received signal. Using the filter, sampling at half the rate can occur and using the MLSE algorithm, the effects of the low-pass filtering can be countered. And because of the low-pass filtering, reduced bandwidth opto-electronics can be used which reduces cost.

This low-power approach is possible because the reach requirements in metro, up to 1,000km, is shorter than long haul/ ultra long haul optical transmission links. The shorter-reach requirements also impact the forward error correction codes, needed which can lessen the processing load, and the components, as mentioned. "We can tolerate greater [signal] impairments which means the requirements on the components we can use are more relaxed," says Shabtai.

The company also revealed that the MP2100C coherent device will integrate the transmitter and receiver on-chip. 

MultiPhy says it is working with several system vendor and optical module partners on the IC development. Shabtai expects the first industry products using the chip to appear in 2014 or 2015. The timing will also be dependent on the cost and power consumption reductions of the accompanying optical components.

A 100Gbps direct-detection optical module showing MultiPhy's multiplexer and receiver ICs. The module shown is a WDM design. Source: MultiPhy

100Gbps direct detection multiplexer chip

MultiPhy has also announced a multiplexer IC for 100 Gigabit direct detection. The start-up can now offer customers the MP1101Q, a 40nm CMOS multiplexer complement to its MP1100Q receiver IC that includes a digital signal processor to implements the MLSE algorithm. The MP1100Q was unveiled a year ago. 

Testing the direct-detection chipset, MultiPhy says it can compensate +/-1000ps/nm of dispersion to achieve a point-to-point reach of 55km. No other available solution can meet such a reach, claims MultiPhy. 

MultiPhy's direct-detection solution also enables 10 Gigabit-per-second (Gbps) opto-electronics components to be used for the transmit and receive paths. At ECOC, MultiPhy announced that it has used Sumitomo Electric's 10Gbps 1550nm externally-modulated lasers (EMLs) to demonstrate a 40km reach. 

Using such 10Gbps devices simplifies the design since no 25Gbps components are required. It will also enable more optical module makers to enter the 100 Gigabit marketplace, claims MultiPhy.  "It is twice the distance and about half of the cost of any other solution on the market - much below $10,000," says Shabtai.

MultiPhy's HQ in Ness Ziona, Israel

The multiplexer device can also be used for traditional 4x28Gbps WDM solutions to achieve a reach in existing networks of up to 800km.

MultiPhy says that it expects the overall 100 Gigabit direct detection market to number 4 optical module makers and 4-5 system vendors by the end of 2012. At present ADVA Optical Networking is offering a 100Gbps direct-detection CFP-based design. ECI Telecom has detailed a 5x7-inch MSA direct-detection 100 Gigabit module, while Finisar and Oclaro have both announced that they are coming to market with 100Gbps direct-detection modules.