Coherent Turns 5

This week marked the fifth anniversary of Nortel Networks announcing its coherent technology. Mike Adams (who's now a vice president at Ciena Corp.) clued me in on it Thursday. Sure enough, it was mid-March 2008 when Ryan Lawler (who's now doing things like interviewing Will Arnett) wrote: Nortel Trots Out 40Gig. We didn't call it "coherent" then. Nortel was emphasizing the name of the modulation scheme, the oh-so-catchy dual-polarization quadrature phase-shift keying (DP-QPSK). Not everyone believed in coherent from the get-go, Adams remembers -- and why not? Nortel's would be one of many different, incompatible 40Gbit/s schemes to emerge for optical line-side transmission. But Nortel got some carriers on board quickly. And months later, coherent detection became the de facto 100Gbit/s standard when the OIF set its 100Gbit/s framework, including the choice of DP-QPSK as the sole modulation format. (See Nortel Rolls On With 40-Gig and OIF Steps In to Fill the 100G Void.) Now at the 2013 OFC/NFOEC, coherent is all we'll talk about, although there'll be some quadrature amplitude modulation (QAM) to go along with the DP-QPSK. We did give Nortel a lot of credit for trailblazing 100Gbit/s coherent (at least, that's how I remember it), but the five-year mark still provided a nice excuse to pause and reflect for a minute. Now back to OFC/NFOEC planning. — Craig Matsumoto, Managing Editor, Light Reading