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Startup Gets Flexible

Light Reading
News Analysis
Light Reading
2/28/2001

Startup Optical Crosslinks Inc. claims it's got the ideal material for optical integration.

It's a polymer. But unlike other polymers, which are coated onto silicon wafers, Optical Crosslinks' stuff is manufactured as a flexible sheet. This gives it quite a few advantages, says director of sales and marketing Lynore Abbott.

A key benefit of the material is "almost no residual stress." That means it doesn't suffer from birefringence (preferred optical directions) and it can accommodate tight bend radii down to just 3 millimeters. (Stress allows light to leak out of fiber bends, for example, because it lowers the refractive index on the outside of the bend.)

Wafer-coating polymers are usually of a type called polyimides. Inside these materials, the molecules are tightly held together so the polymer isn't very flexible, explains Abbot. Optical Crosslinks uses a polyacrylate, in which the bonds between molecules are much longer and looser. "People didn't look at polyacrylate originally because it has a very large temperature dependence," says Abbott. "What we found is, though it expands and contracts, the waveguide properties magically stay the same."

This discovery was made by Dr. Bruce Booth while at Dupont. He spun out the company in 1998, licensed the technology from Dupont, and has never looked back. The startup was originally called Polymer Photonics but changed its name to better reflect its market position.

It has seed funding from telecom executives Chad Paul and John Englesson, Essex Investment Mgt. Co. LLC and a number of private individuals.

Like most companies targeting optical integration, Optical Crosslinks is starting with something simple. It's already selling what it calls a "pitch transition device" to manufacturers of vertical cavity surface emitting lasers (VCSELs -- see Laser Blazers). This is a bunch of tapered waveguides that pipe light from a VCSEL array to a fiber ribbon.

"One of my customers is using a 4x12 VCSEL array," says Abbott. "The closer he can pack those VCSELs [on the wafer], the more money he can make. But he still needs to be compatible with the 250 micron pitch in the fiber ribbon." She figures this to be a huge volume application.

Right now, the product is undergoing Telcordia 1209 and 1221 reliability testing. Optical Crosslinks claims it's closing in on some large OEM contracts and design wins for this product but won't name names. "To our customers, we're the secret advantage," Abbot says.

Future products have not been determined. "There are a million places to apply it," says Abbott. Gratings, couplers, and switches can all be made easily in Optical Crosslinks' polymer, she says. On the startup's Website, there's a white paper featuring pictures of a bubble switch, rather like the one from Agilent Technologies Inc. (NYSE: A) but made from polymer, along with claims that the polymer processing technology will result in a higher performance switch (see Agilent Unveils Optical Switching Breakthrough).

However, it could be a while before products designed to operate with DWDM (dense wavelength-division multiplexing) at around 1550 nanometers become a reality. Abbot says one reason the firm is targeting VCSEL manufacturers in the first instance is because "it will buy us some time so we can work at dropping optical losses" at telecom wavelengths. According to the startup's datasheets, losses are 0.1 dB per cm at 850nm (where the VCSEL arrays operate), but rise to 0.3 dB per cm at 1300nm and 0.7 dB per cm at 1550nm.

It's worth pointing out that other startups have had a lot of trouble reducing losses in optical polymers. Lightwave Microsystems Corp. is one. "We could build a one-off, low-loss [polymer] device, but you need to be able to do it more than once," says Drew Lanza, founder of Lightwave Micro and now a partner at Morgenthaler Ventures. He says that Lightwave Micro hasn't given up on polymers altogether but now views them as a much longer-term goal.

-- Pauline Rigby, senior editor, Light Reading http://www.lightreading.com

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poly anna
poly anna
12/4/2012 | 8:50:10 PM
re: Startup Gets Flexible
Polymers tend to be incredibly difficult to process reproducibly due to many factors. Moisture absorption and gradual polymerization over time were just two of the major roadblocks to making a flexible polymer arrayed waveguide device. Brittleness is another problem with the non- polyimide optical polymers. Also, loss due to particulate contamination has always been a huge problem. Manufacturability is a very big concern, and it will be very expensive to control all the contributing factors, making optical polymers not such a cost effective solution.
the yaz
the yaz
12/4/2012 | 8:50:08 PM
re: Startup Gets Flexible

yes, well, morganthaler has vaunted and world-renowned expertise in optical networking and subcomponent manufacturing.

just look at tachion.

gman
gman
12/4/2012 | 8:49:57 PM
re: Startup Gets Flexible
I must take exception to Poly Anna's remarks. While many of the observations made are typical of prior experiences with polymers, Optical CrossLinks' strength and value proposition is that its process overcomes all of the criticsms listed. If someone is going to make derogatory statements, they'd be well advised to find out the facts first.
Pauline Rigby
Pauline Rigby
12/4/2012 | 8:49:56 PM
re: Startup Gets Flexible
Sorry about that. OXL provided this information over the phone and I would have hoped they'd get that sort of thing correct! However, it doesn't excuse me entirely beacuse I should have cross-checked it with the press release before publishing.

I will fix the article.

[email protected]

Gman wrote:

The investor information provided in the recent articles on Optical CrossLinks (OXL) are incorrect. I believe the information listed with regard to $40Million invested by Goldman Sachs and Kodiak refer to one of OXL's VCSEL customers. OXL's funding to date was accomplished through a Series A round led by telecom executives Chad Paul and John Englesson together with Essex Investment Mgmt. Co. and a number of private individuals.
gman
gman
12/4/2012 | 8:49:56 PM
re: Startup Gets Flexible
The investor information provided in the recent articles on Optical CrossLinks (OXL) are incorrect. I believe the information listed with regard to $40Million invested by Goldman Sachs and Kodiak refer to one of OXL's VCSEL customers. OXL's funding to date was accomplished through a Series A round led by telecom executives Chad Paul and John Englesson together with Essex Investment Mgmt. Co. and a number of private individuals.
OXL CEO
OXL CEO
12/4/2012 | 8:49:54 PM
re: Startup Gets Flexible
With regard to the article on Optical CrossLinks some clarifications are needed. Our VCSEL interface products involve precisely stacked arrays of waveguides for various customers covering a broad range of array interconnects, not any specific array such as the 4x12 noted in the article. In addition, our multi-layer pitch change stacked arrays interface to fibers at the standard 250 micron spacing and to VCSELs at 100 micron or less center to center spacing for extremely high density interconnections, thus the dramatic space and cost savings as mentioned in the article. Polymer material developments underway are aimed at lower losses at 1550nm, however our current product focus on 1550nm devices is directed at dense optical switch arrays and Bragg grating WDM devices with a small postage stamp size footprint. Combining this small size with our low loss connectivity and dense guide structure enables us to provide highly competitive devices where the material losses are not a factor.
ESBinkley
ESBinkley
12/4/2012 | 8:49:51 PM
re: Startup Gets Flexible
If Optical Crosslinks can indeed reduce the attenuation of their polymer waveguide materials at telecom wavelengths they clearly will have a big winner. The processing advantages and integration possibilities of polymer photonics are substantial. Reproducible, high volume, low cost manufacturing is the key to commercial success, and, contrary to perception, there are several companies doing that today.
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