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Optical/IP

Genoa Amps Up

Today Genoa Corp., a three-year-old startup in Fremont, Calif., is unveiling the details of its first chip-based amplifier product.

The company is also announcing that it has closed a $75 million third round of funding from lead investor August Capital, together with Bessemer Venture Partners, Global Crossing Ventures, Investor AB, Levensohn Capital, Meritech Capital Partners, Oak Investment Partners, and WorldCom Ventures.

Genoa says it’s making an optical amplifier for metro networks that will be what the transistor was to electronics –- a smaller, cheaper way to boost signals that will result in better economics for equipment makers. The company appears to have invented a semiconductor optical amplifier (SOA) that incorporates a built-in vertical cavity surface emitting laser (VCSEL) to provide gain control (see Laser Blazers).

Just like any other SOA, Genoa's gadget is designed to transform a weak signal into a stronger one. But unlike a regular SOA, it purports to amplify dozens of different wavelengths of light without distortion or “cross talk" (see SOAs Not DOA).

Regular SOAs can't amplify more than one wavelength at a time, because it’s hard to control the amount of gain (or amplification) they provide. When signals are added, dropped, or switched, the optical power level inside the device fluctuates and alters the gain. When more than one wavelength is shoved through an SOA, the signals start taking on each other's characteristics.

Here’s roughly how Genoa’s tackled the problem: It's saturated the gain of the amplifier by flooding it with light from another laser. Any fluctuations in the power of the data channels appear inconsequential compared to the optical power generated by the laser.

Genoa also says it has monolithically integrated the laser with the SOA. Signals that need boosting pass horizontally through the device, while the light from the laser bounces vertically up and down.

“We’ve created a very, very high intensity light inside this chip... without changing the operating condition of the chip itself,” says Rick Gold, Genoa’s president and CEO.

If it works as described, Genoa's amplifier could do for metro networks what erbium doped fiber amplifiers (EDFAs) have done for long-haul networks, says Gold. But whereas EDFAs allow light to travel longer distances, Genoa’s chip will be used to compensate for loss introduced when packet processing takes place at each network node.

Some experts think Gold's got a point. Such a component development could pave the way for more all-optical technologies being used in metro networks.

“Because [Genoa’s amplifier] is so small, so inexpensive, and consumes so little power... then you can think about putting all-optical switches in metro networks without having to worry about loss,” says Scott Clavenna, president of PointEast Research LLC and director of research at Light Reading.

A cheaper amplifier for metro networks might also kick-start metro DWDM alternatives, such as CodeStream Technologies Corp.'s optical code-division multiple access (OCDMA) (see Metro DWDM: Not the Only Game in Town).

There's no doubt that Genoa’s approach is innovative. It was, after all, one of the few projects to get funding from the federal government's Advanced Technology Program (ATP) last year (see Out of the Lab: The Cream of the Trough).

But Genoa won't have the world of metro amplification to itself. SOA startups like Kamelian Ltd. and Optospeed SA, while targeting the long-haul space, will eventually be able to bring down the costs of successive products enough to make them feasible for metro applications. JDS Uniphase Inc. (Nasdaq: JDSU; Toronto: JDU), Nortel Networks Corp. (NYSE/Toronto: NT), Ericsson AB (Nasdaq: ERICY), Corning Inc. (NYSE: GLW), and Lucent Technologies Inc. (NYSE: LU) also make EDFAs refashioned for metro networks and are likely developing cheaper alternatives as well.

Genoa will ship beta samples to customers by this summer and will ship commercially by the end of the year, Gold says.

-- Phil Harvey, senior editor, Light Reading http://www.lightreading.com
Toto 12/4/2012 | 8:44:56 PM
re: Genoa Amps Up Alcatel and Uniphase (acquired from Philips) had SOA for 1.5 micron back in 97. Methode of using a laser to lock amplifier gain has been in the field since 98. Nothing is really new, except - well, SOA and laser on the same chip. But it's just a question of putting mirrors on part of SOA chip to make it laser. Laser = amplifier+mirror.
Most importantly, SOA not just provides little gain, the worst part is it creates 2 times noise than EDFA.
blbeast 12/4/2012 | 8:43:28 PM
re: Genoa Amps Up
Traditional SOAs are plagued by the challenges of dual pigtail alignment (losses taken right out of the amplifier gain), ripple effects, polarization dependence, and crosstalk. The VCSEL pumping may take care of the crosstalk problem, but does Genoa solve the other major limitations?
tonimele 12/4/2012 | 8:28:36 PM
re: Genoa Amps Up Has anybody tested LOA devices?
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