Optical/IP Networks

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Seeing how Agere's device compares to these competing products is not straightforward, however, because vendors do not quote figures of merit in the same way.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

SectorInvestor 12/4/2012 | 8:21:30 PM
re: Agere Claims 40-Gig First They are developing a breakthrough disruptive optical technology that creates active optical components DIRECTLY in optical fiber, eliminating the need for any planar optical chips.

The process involves the use of their fully patented polarization maintaining "D" fiber, that theyalso produce inhouse. The unique shape of the fiber allows easy access to the fiber core. By etching out the fiber core and replacing it with hgh speed polymer material, they will be able to produce an entire family of optical components at any speed up to 100+GHz, with better specs and price/performance than any non-polymer based components.

The first product will be a 40Gbps modulator. They will have samples this year, and will be in production early in 2002. KVH has over 20 years of experience in the fiber optic field. The optical components are an addition to a line of Fiber Optic Gyros and sensors.

Details on their ActiveFiber all-fiber technology can be found at http://www.photonicfiber.com/ and the preliminary specs of their 40Gbps modulator can also be found there.

CarboCat 12/4/2012 | 8:20:07 PM
re: Agere Claims 40-Gig First The D fiber technology combined with NLO polymers may be a good idea but KVH says their photonic fiber modulator has long term stability over a wide temperature range but they don't quote actual numbers. What do they mean? How about photo-depoling? How about the total device loss?
SectorInvestor 12/4/2012 | 8:20:00 PM
re: Agere Claims 40-Gig First You are pretty much looking at all the information known to us at this time.

Total device loss should not be much higher than the insertion loss because the light never leaves the fiber core and the polymer has virtually the same optical characteristics as the fiber core. The total length of polymer in the fiber is only a few centimeters which should compare very favorably to devices using planar optical chips.

What should also be mentioned is that because the optical chip is eliminated in the component, the problem with low yields (which can be as low as 5% at the OC-192 level) is eliminated as well. The low production costs may allow KVH a significant pricing advantage over competition.

They are attending the major NFOEC optical conference in early July and I expect more details will be announced then.
CarboCat 12/4/2012 | 8:16:46 PM
re: Agere Claims 40-Gig First If you look at the schematic the electorde seems to be buried in the fiber. Depending on the cladding thickness this coulg give a very lossy device. Also, if they're using any of the standartd "push-pull" dyes nonlinear absorbtion/scattering may be a problem.
Still a very cool Idea.
SectorInvestor 12/4/2012 | 8:15:58 PM
re: Agere Claims 40-Gig First I meant to add this excerpt from the Patent tat addresses the question.

"A typical fiber used in fiber optics consists of core, cladding, and outer protective layer. The core and the cladding have different indices of refraction and together form a guiding region
for an optical signal. The difference in refractive indices enables properly directed light to be internally reflected at the core-cladding boundary. Thus, the optical signals will be guided
down the core and will not be lost into the cladding. The outer protective layer is used to increase mechanical strength of the fiber and allow the fiber to be more easily manipulated. "
SectorInvestor 12/4/2012 | 8:15:58 PM
re: Agere Claims 40-Gig First On the contrary, the electrode is sufficiently close to the core that losses are very low. They have a patent on the groove technology. You can read about it.'6134356'.WKU.&OS=PN/6134356&RS=PN/6134356

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