Mode-filtered optical amplifier technology wins R&D 100 Award
August 28, 2007
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Sandia National Laboratories and the Naval Research Laboratory have been honored with one of this year's R&D 100 Awards for their development of mode-filtered optical amplifier technology. The principal inventors are Dahv Kliner, Jeffrey Koplow, and Lew Goldberg. Mode filtering can allow fiber amplifiers to scale to very high output powers, potentially revolutionizing the laser market.
The R&D 100 Awards, presented every year since 1963, have been billed as “the Oscars of invention” by the Chicago Tribune. The awards aim to recognize the “100 most technologically significant new products” of the year. To be considered significant, an invention should address large, broad-based needs, offer dramatic, orders of magnitude improvements over existing technologies, and possess what judges call the “Wow! factor.”
The award-winning mode-filtered amplifier technology increased the power scaling limits of fiber amplifiers by more than 100 times, enabling the production of multiple kilowatts of output power in a single-mode (i.e., tightly focused, low-divergence) beam.
This advancement opened the door to use fiber amplifiers in many real-world applications such as materials processing, remote sensing, and more. Fiber-based devices have substantial advantages over competing technologies, including far superior beam quality, wavelength flexibility, electrical efficiency, waste heat generation, maintenance requirements, and package size.
Sandia's award application cites Nufern as one of the first companies to bring a commercial product to market based on the invention. The paper describes a 180-Watt mode-filtered fiber laser produced by Nufern, with electrical efficiency 7 times greater than a traditional Nd:YAG laser. Nufern has licensed the patent related to this mode-filtering technology from the U.S. Government, and is also the leading manufacturer of “large mode area” optical fibers useful for mode filtering.
The invention is notable for its simplicity. High-power amplifier fibers with large core sizes allow many “modes” of light to travel through them, resulting in a relatively unfocused beam. By strategically coiling the fiber around a chosen radius, it is possible to induce bend loss, stripping out higher order modes of light while allowing the fundamental mode to travel through the fiber unimpeded. This mode filtering is achieved with no side effects upon the other performance characteristics of the beam. It essentially converts what would have been an undesirable multimode fiber amplifier into a much more desirable single-mode amplifier, while retaining the benefit of using an optical fiber with a larger core size.
Over the years, the R&D 100 Awards have recognized winning products with such household names as Polacolor film (1963), the flashcube (1965), the automated teller machine (1973), the halogen lamp (1974), the fax machine (1975), the liquid crystal display (1980), the printer (1986), the Kodak Photo CD (1991), the Nicoderm antismoking patch (1992), Taxol anticancer drug (1993), lab on a chip (1996), and HDTV (1998).