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Electronics takes centre stage

With 100G and coherent receivers, a lot of the complexity in the components moves from the optics to the electronics.

Ed Cornejo of Opnext tells me that the company is working on a coherent solution for 100 Gbit/s transmission, and will have a demonstration of this capability by the summer. The vendor is doing in-house development for the electronics piece of the puzzle, where much of the complexity lies; in Cornejo’s view other optics companies will face a significant barrier if they don’t have this expertise. Opnext’s electronics know-how came from Stratalight of course, which started out as a subsystems developer, and had been working on digital signal processing prior to the merger with Opnext. “We should have the best cost structure of anyone doing 100G,” he claims. “It’s going to be lower cost than what’s out there today, because we’re doing it in CMOS.”

One vendor that does have that electronics focus is CoreOptics, which is both a chip maker and a module maker, with experience in digital signal processing (DSP) coming from the development of MLSE algorithms for electronic dispersion compensation. The company issued a press release at the show claiming that it has validated its “coherent” technology for cost-effective 40G transmission (their quotation marks, not mine). What this means, I have absolutely no idea. CoreOptic’s senior marketing folks were ensconced in a room with a systems vendor when I turned up to meet with them, so I’m still in the dark.

One thing I’ve learned this week is that, strictly speaking, “coherent” is a term that can be applied to any modulation scheme that uses phase to encode the information, whether the detection scheme is differential (comparing the phase of one bit with the next using optics) or uses a local oscillator laser and DSP to extract the signal. So CoreOptic’s approach could be either.

Posted by Pauline Rigby on March 25, 2009 7:33 PM | Permalink