What could turn out to be a significant development in transmission systems is being cooked up at Unique-mode AG, a startup based in Jena, Germany, that recently announced another round of funding (see Laser Diode Startup Gets Funding).

The company, a spinoff of the Fraunhofer Institute, is making pump lasers that could be put to use in Erbium Doped-Fiber Amplifiers (EDFAs), devices that boost the power of light signals in fibers. The pump lasers that it’s making, however, are up to 10 times more powerful than the ones currently used in EDFAs.

EDFAs work by pumping light into the cladding surrounding the core of fibers in a way that re-energizes the light signals passing through the core. The power of the pump lasers employed to do this determines the spacing of the EDFAs, which are fairly expensive animals to buy, install, and maintain.

Unique-mode makes two versions of its diode laser, delivering 2.81 or 5.2 watts of output power. The emitter itself pumps out up to 6 watts and shapes the light so that it can be coupled into a fiber with a small core (50 or 100 micron) with “high efficiency,” according to Albrecht Pfeil, head of sales and marketing at Unique-mode. It achieves this by its patented optics technology, lenses, and assembly, he adds. Current pump lasers used in EDFAs max out at a mere 500 milliwatts.As one might expect with Unique-mode’s huge leap in pump laser power, there’s a catch. The lasers are multimode rather than singlemode, which is somewhat ironic, considering the company name.

Up until now, EDFA manufacturers have used singlemode lasers, but that could be about to change, according to Jacob McKenzie, a researcher at the University of Southampton who has been testing Unique-mode’s equipment. “Multimode is not a big issue anymore,” he says, contending that new double-clad, large-mode area fiber cable is “more than adequate” for EDFAs and allows the use of multimode pump lasers.

What makes these remarks particularly pertinent is that the EDFA was invented by Professor David Payne, director of the Optical Research Center at Southampton and chairman of Southampton Photonics Inc., a startup making EDFAs that was spun out of the center.

Southampton Photonics has taken delivery of some Unique-mode pump lasers and is experimenting with them, Light Reading has learned. Other American and Swiss telecom equipment manufacturers are also playing with the German startup’s lasers.

All the same, it’s early days. The jury is still out on whether these experiments will bear fruit. “No one knows for sure if multimode will replace singlemode in telecommunications applications,” admits Albrecht Pfeil.

“It’s all research and development right now. We are looking for a partner diode laser supplier to drive the approval/qualification phase for the components,” says Pfeil, who is also a founder of Unique-mode. So far, the startup has been selling its optics for non-telecom applications, namely, medical systems.

Unique-mode sources its emitters from the likes of JDS Uniphase Inc. (Nasdaq: JDSU; Toronto: JDU), Sony Corp., and Spectra-Physics Inc. (Nasdaq: SPLI), then packages them with its optics in a “slightly larger than butterfly form" in its own clean-room facilities. The next phase is to quadruple manufacturing space to go to high volume production of its shapers.

Unique-mode currently has 17 on staff and is being funded in stages by DEWB AG, the venture capital arm of the Jenoptik Group, a 10 year-old company whose two other divisions develop and manufacture photonics and clean-room equipment. Though Pfeil would not disclosed the value of DEWB’s investment, Unique-mode’s founders maintain 60 percent of the company, while DEWB has acquired 35 percent and the Fraunhofer Institute still owns 5 percent of the shares.

The startup, founded in February 2000, is one of three that have spun out of the Fraunhofer Institute for Applied Optics and Precision Engineering in Jena. The other two spinoffs are MSO Jena Mikroschichtoptik GmbH, which makes optical coatings, and Grintech GmbH, a startup that develops and manufactures gradient index lenses and lens systems for applications in telecommunication, diode laser beam shaping, and endoscopy.

— Valerie Thompson, special to Light Reading
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