Polychromix touts new optical dispersion technology

October 18, 2004 Wilmington, MA -- Polychromix Inc. recently received a $500,000 grant from the National Science Foundation (NSF) to commercialize a new type of optical dispersion element based on a proprietary combination of diffractive gratings and thin-film technology. Polychromix hopes to have the device, dubbed the Interfractor, commercialized and ready for deployment within the next 12 to 24 months, reports Lightwave News Editor Meghan Fuller.

Oct 18th, 2004

October 18, 2004 Wilmington, MA -- Polychromix Inc. recently received a $500,000 grant from the National Science Foundation (NSF) to commercialize a new type of optical dispersion element based on a proprietary combination of diffractive gratings and thin-film technology. Polychromix hopes to have the device, dubbed the Interfractor, commercialized and ready for deployment within the next 12 to 24 months, reports Lightwave News Editor Meghan Fuller.

Critical DWDM equipment, including dynamic gain equalizers, reconfigurable wavelength blockers, reconfigurable optical add/drop multiplexers (ROADMs), and wavelength-selectable switches, require spatial separation of the wavelengths from the input fiber, typically achieved with a diffraction grating.

Diffraction gratings have existed since the early 1800s and are currently used in a variety of applications, including telecommunications and spectroscopy. There is ongoing research to use the technology for display applications as well. But regardless of the industry or application, diffractive gratings contribute "a fair amount of optical loss to your system," admits Mouli Ramani, vice president of business development and marketing at Polychromix.

The problem with diffraction gratings is their susceptibility to polarization effects. A grating will have some transmission capability for a certain polarization of light but a different capability for any other polarization, which creates a variation that translates in different devices to polarization dependent loss (PDL), for example. This phenomenon is related to the grating's efficiency; the higher the grating efficiency, the less susceptible it is to variations in polarization.

Until now, diffractive gratings have required a tradeoff, says Ramani, between efficiency, polarization independence, and dispersion. "Any time you, as an engineer, try to put this in any system, you have to make these tradeoffs. What we have been able to patent is a truly new and unique way to look at diffraction gratings."

Polychromix uses a reflective relief grating, adds a dielectric fill and then covers the grating with a very thin film or dielectric overcoat. "We basically combine the best of the diffractive gratings and the best of thin film technology to create a combination whereby you don't have to make that Hobbesian choice between efficiency and polarization independence," says Ramani.

The new technology provides improvements both in insertion loss and the polarization dependence of the loss. The amount of dispersion--or the width of the light spectrum as it hits the grating--is also improved, and this directly impacts the size of potential devices build on the technology. "If you can only disperse the light into a very narrow cone, you would have to build a very elongated device," explains Yariv Geller, director of business development at Polychromix. "But if you can spread it very widely, you can build a lot more compact devices, which obviously have benefits in systems."

Another key advantage is the manufacturability of the device. "In general, what we're using is typical semiconductor microlithography, which is something that we are very familiar with here at Polychromix because we use MEMs technology," notes Geller. "This is obviously going to be much simpler to manufacture than a MEMS device that has a more complex structure that needs to move. Here, we are basically taking a few semiconductor layers and doing the standard manufacturing processes."

The market potential

In 2003, Polychromix won the Phase I portion of the NSF grant--$100,000 to do a feasibility study to determine the viability and manufacturability of the device. According to Winslow Sargeant, manager of the NSF's Small Business Innovation Research (SBIR) program, only 10% of all proposals receive Phase I funding, and then only 40% of those proposals make it to the Phase II level. As a Phase II award recipient, Polychromix receives $500,000, to be dispersed over the next 24 months.

When asked why the NSF decided to fund the Polychromix proposal, Sargeant cited the company's reputation for innovation as well as the strength of the technology itself--in particular its manufacturablity and market potential. "At the Phase II level, we look not only at the technology, but at the marketplace as well," he reports. "We bring in an another team of experts who understand the marketplace, and they can read a good commercialization plan. From that, we'll make the determination as to whether the proposal should be funded."

The Interfractor product has been on the Polychromix drawing board for quite some time, admits Ramani, but the company now plans to accelerate commercialization of the device to meet the NSF's requirements--"probably within 12 to 24 months," he says. While the company plans to incorporate the Interfractor technology into its existing product portfolio, including the Polychromix Dynamic Channel Orchestrator (P-DCO), Geller reports that the company hopes to sell the productized technology to non-competitive industries as well.

--MJF

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