Startup Strikes Gold

Danish startup plans to develop integrated optical components that employ exotic optical effects in thin gold films

September 21, 2001

4 Min Read
Startup Strikes Gold

Danish startup Micro Managed Photons A/S (MMP) (no Website) plans to develop integrated optical components that exploit some exotic optical effects in thin gold films (see Danes Break Through in Optics).

The company was founded by a group of five researchers from Ålborg University and Research Centre COM at the Technical University of Denmark -- an institute that has spun out several optical companies in the past few years, including Ionas A/S, a foundry for integrated optics, and Crystal Fibre A/S, which makes photonic crystal fiber.

Research Centre COM's newest venture, which was founded last month, is also based on photonic crystals -- periodic microstructures that give engineers a new way to control light. These materials hold the promise of being able to guide light around sharp bends with no losses, thus offering a way of shrinking optical integrated circuits.

"The basic idea is to downscale integrated optics," says Jørn M. Hvam, a team member from Research Centre COM. He believes it will be possible to reduce the size of integrated optical components "by a factor of 100 or more".

R&D Labs around the world are looking at ways of using photonic crystals to shrink optical integrated circuits (see The Hole Thing), and at least one startup has been formed to try and bring these ideas to market (see Crystal Startup Gets $4M). Most of these are considering structures based on a semiconductor wafer perforated by a repeating pattern of holes. Waveguides are created by missing rows of holes in the otherwise perfect pattern, thus providing a path through which the light can travel. (To see a picture of this, click on

But there's one problem with this approach. In the plane of the wafer, light traveling through a waveguide "sees" a series of interfaces in the holes, which are responsible for the so-called "photonic bandgap" effect that prevents light from leaking out. However, in the direction above and below the waveguide, there are no interfaces, so light can escape. To keep optical losses at a reasonable level, a way must be found to prevent the light from seeping away.

MMP says it has the answer. It's found a mechanism that keeps light confined in the plane of a glass wafer. Without going into details, this happens at the interface between a metal and a dielectric, hence the need to use gold. The technical term is a "surface plasmon polariton", or simply a surface wave.

By making a regular array of bumps in the gold film, it's possible to have a photonic bandgap effect to create waveguides. The bumps in the gold are the equivalent of the holes in the semiconductor, says Hvam. This should reduce optical losses significantly.

Hvam also claims that it's much easier to make bumps in gold films than it is to make holes in semiconductors, which should lead to much cheaper manufacturing.

The researchers have been working on this idea for the past two years, and have proved the principle of making a waveguide using a gold film on a glass substrate. Now they have seed funding of DKK 32 million (about US $4 million) to develop their ideas further. The cash was provided by Danish venture funds Wise Venture and CAT Seed.

On the face of it, it sounds like a classic case of VCs funding a research project, since MMP doesn't expect to have any product prototypes for three years. Hvam acknowledges that the company has a lot of work to do, particularly on how to integrate active components with passive waveguides. However, he says the startup has enough cash already to see it through to these goals.

That's very important, as other startups with long-term goals have gone under or been forced to refocus because they ran out of money before reaching significant milestones (see Nanovation Up For Sale, for example).

Although MMP received its cash several weeks ago, its official start date is not until November. "We need to hire some people before we can really say we've started," says Hvam. He plans to recruit 4 to 6 PhDs and a couple of admin staff initially.

— Pauline Rigby, Senior Editor, Light Reading

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