Agere Claims 40-Gig First
Agere Systems Inc. today claimed that it was sampling lithium niobate-based modulators that promise to extend the distance of 40-Gbit/s transmissions (see Agere Intros 40-Gig Modulator).
The modulator has a particularly low drive voltage of 2.5 volts (referenced at 1 GHz) and a guaranteed minimum bandwidth of 30 gigahertz, according to Agere.
"The tradeoff in reducing the required drive voltage is usually lower bandwidth, but Agere has achieved this power reduction without affecting bandwidth or cost," says Agere's product marketing manager Ken Newton.
"A lot of our competitors spec their devices below 30 GHz even though they're running them at 40 Gbit/s," notes Newton. "Their devices will still pass a 40-gig signal, but it will have a greater eye closure [signal degradation]. Bottom line? It won't go so far."
Newton says that Agere's main competitor in the lithium niobate modulator space is Sumitomo Corp.. He's also keeping an eye on startup Codeon Corp., which is shipping 40-gig modulators and has announced a design win with Siemens AG (NYSE: SI; Frankfurt: SIE) (see Codeon Bets on Clever Crystals and Siemens to Trial Codeon Modulators).
Seeing how Agere's device compares to these competing products is not straightforward, however, because vendors do not quote figures of merit in the same way. Drive voltages can be quoted at different speeds for the same application. Agere's modulator actually requires about 3.5 V to operate at 40 Gbit/s (As noted, it reports a figure of 2.5 V for a lower speed of 1 GHz). Other vendors note numbers for steady state or DC conditions, and some forget to state what conditions apply. On datasheets available on its Website, Codeon lists a bandwidth of 22 GHz and a voltage of 4 V. It doesn't say at what speed that voltage was referenced.
Polymer technologies are starting to emerge and could pose a challenge to lithium niobate devices. For example, Pacific Wave Communications claims to have developed a polymer modulator with a bandwidth of 40 GHz -- better than Agere's product -- and DC drive voltage of less than 4 V under DC conditions. And there are other companies working on high-speed polymer devices, including Lumera Corp. (see Polymer's Progress and Cisco Invests in Lumera) and KVH Industries Inc. (Nasdaq: KVHI) (see Optical Fibers Go Active).
— Pauline Rigby, Senior Editor, Light Reading, http://www.lightreading.com