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SAN ANTONIO, February 20, 2003. Dr Johan Nilsson of SPI (Southampton Photonics, Inc.) and the ORC (Optolectronics Research Centre) at the University of Southampton, presented results at the ASSP (Advanced Solid State Photonics) Conference in San Antonio in early February, further demonstrating the important and rapid advances being made in cladding-pumped fiber laser technology.
In published experiments, 3.5 W of output power at 980 nm from a Jacketed Air-Clad (JAC) ytterbium-doped fiber laser was demonstrated in a nearly diffraction-limited beam. This is believed to be a world record power at this all-important wavelength.
980 nm fiber lasers have important applications in telecommunications and aerospace where they can be used to pump multiple Erbium Doped Fiber Amplifiers. When frequency-doubled to 490 or 488 nm they are the replacement candidates for argon ion lasers for use in instrumentation in many analytical and bio-medical applications.
For some time, laboratories worldwide have attempted to produce a single-mode
980 nm fiber laser, however, the dopant of choice, Ytterbium, stubbornly reabsorbs light generated at 980 nm and emits at around 1040 nm.
Nilsson presented a threefold solution to the problem: First, a high-brightness pump module is used that can deliver 5 W of multimode power in a 35 um beam; secondly, a special fiber is fabricated that has a 35 um cladding suspended in air. This high NA "Jacketed Air Clad" (JAC) fiber preserves the brightness of the 915 nm pump radiation and reduces the threshold for the 980 nm emission from 250 mW to 400 mW. Finally, the JAC fiber utilizes SPI's patented ring-doping technology whereby the Ytterbium ions are incorporated in a ring around a single-mode core. Ring-doping reduces the re-absorption of the 980 nm emission and, moreover, reduces the gain from the unwanted 1040 nm radiation. The result is a laser providing 3.5 W of single-mode 980 nm radiation with a 400 mW threshold and 42% slope efficiency.
With the important reductions in cost of ownership and unit size, combined with their greater reliability and longevity, fiber lasers have many advantages over conventional laser technology.
Stuart Woods, SPI's Director of Business Development, commented, "SPI continues to push the fiber laser applications space through our work on specialty fibers and we see a day when many applications currently addressed by traditional solid state and ion lasers, can be substituted on a one-to-one basis by a fiber laser".
SPI is at the forefront of a revolution in the design and manufacture of optical components, delivering state-of-the art products that are driving down the cost of ownership for its customers in the industrial, aerospace, analytical, communications and sensing markets. SPI's innovations in high-power fiber lasers, amplification and wavelength management are underpinned by its unique, patented specialty fiber technology and manufacturing capability. SPI's current product range includes: fiber lasers and laser arrays, high-power optical amplifiers and sources, filters (fiber Bragg gratings), combining optics and dispersion compensators. SPI's gratings have the world's lowest distortion and combined with their ultra-low dispersion, make them very easy to use.
Military & Aerospace Electronics
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