Next-Generation Optical Fiber Fabrication


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FIRST developed in the 1970s, thin, flexible, and transparent optical fiber revolutionized the telecommunications industry, acting as the structure for carrying electromagnetic waves from point to point. Because of its large bandwidth and immunity from electromagnetic interference, optical fiber has largely replaced copper wire for transmitting data over long distances—across the country, for example.

An optical fiber can also be made into a laser by mixing rare-earth ions into the fiber’s glass structure and pumping those ions with a separate laser diode, such as the diodes that generate the light in a laser pointer. Fiber lasers can take this concept a step further, combining the power of many inexpensive laser diodes into a single coherent beam. The fibers are especially well suited for scaling up high-power, continuous-wave lasers that emit a steady stream of photons. Commercial laser systems have reached average powers of 10 kilowatts, high enough to cut and machine metal parts for the automotive and heavy-equipment industries.

Because fiber lasers are compact and reliable and their beams can be focused to extremely small, diffraction-limited spots, they have also found a niche in scientific applications. In this area, however, their performance is limited. They work well for tasks in which energy is spread evenly over time—the metaphorical equivalent of slowly pushing a tack into a board with your thumb—but not for applications that require energy bursts—akin to hitting a nail with a hammer. That’s because the fiber’s small cross section lets it amplify pulses to levels that damage the fiber itself.

Unlike the bulk fibers produced by the telecommunication industry, which are completely solid and circularly symmetric, Livermore researchers have developed intricately detailed ribbon-like photonic crystal fibers made designed to handle some serious power coursing through them.

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Next-Generation Optical Fiber Fabrication

  1. 1. LLNL-PRES-773886 This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. Lawrence Livermore National Security, LLC Dr. JayW. Dawson, FiberTechnologies Group Leader
  2. 2. Lawrence Livermore National Laboratory LLNL-PRES-773886 2  Fibers • Diffraction limited beams • Robust, flexible transport • Operate in extreme environments and insensitive to electro-magnetic interference  Fiber Lasers • Low maintenance & high reliability • Efficient (>30% wall-plug) • High average powers (kW)
  3. 3. Lawrence Livermore National Laboratory LLNL-PRES-773886 3 Telecom Flexible Delivery for Industrial Machining High Power Laser Sources Distributed Sensors Short-pulse surgery laser delivery Sensors for Oil and Gas HighVoltage Current Sensors These are examples of a wide array of potential applications in flexible light transport, sensors and components for laser systems.
  4. 4. Lawrence Livermore National Laboratory LLNL-PRES-773886 4 Cross section: 125 µm O.D. Very low losses attainable Strong and Flexible 50% transmission over 30km
  5. 5. Lawrence Livermore National Laboratory LLNL-PRES-773886 5 Diffraction Photonic crystal fiber Refraction Conventional fiber
  6. 6. Lawrence Livermore National Laboratory LLNL-PRES-773886 6 P = 0.065 W P = 1.1 W P = 2.4 W Optical Near Field Optical Far Field 250 µm 200 µm 10 µm X 120 µm Yb3+ Slab Waveguide Secondary Waveguide for Diode Pump Light 0 1 2 3 4 5 6 0 5 10 15 20 OutputPower,W Coupled Pump Power, W 5 W at 44% optical efficiency Example: investigation of rectangular core fiber lasers for improved power scaling
  7. 7. Lawrence Livermore National Laboratory LLNL-PRES-773886 7 Proposed Design Calculated Waveguide Modes
  8. 8. Lawrence Livermore National Laboratory LLNL-PRES-773886 8 Computer Model Manufacturing Design
  9. 9. Lawrence Livermore National Laboratory LLNL-PRES-773886 9 Raw Material Draw to ~1mm rods and tubes Stack to Fiber Design Final Preform in Furnace Fiber Production Draw Tower
  10. 10. Lawrence Livermore National Laboratory LLNL-PRES-773886 10
  11. 11. Lawrence Livermore National Laboratory LLNL-PRES-773886 11 215 µm Passive Ribbon Fiber 200 µm 250 µm Yb3+ Ribbon Fiber 250 µm UV Rad Hard Qualification Fiber Hollow Core Cane (preform) Negative Curvature Core for mid-IR
  12. 12. Lawrence Livermore National Laboratory LLNL-PRES-773886  Hollow core waveguides for high power transport  Short wavelength fiber lasers (<1µm)  UV radiation hard fibers for NIF  Three SBIR collaborations • 2 defense, 1 medical • Joint proposal development opportunities 12
  13. 13. Lawrence Livermore National Laboratory LLNL-PRES-773886 13 hollow single mode R&D 100 Award  Discerned fiber limits1  Pioneered ribbon fiber2  Launched high-order modes3 (R&D 100 Award, 2013)  Power scaling in ribbon lasers4  Designed new type of fiber5,6,7  Developing a 1,000+ core fiber for the National Ignition Facility 1. J. Dawson et al, Opt. Exp. 16 13240-13266 (2008). 2. D. Drachenberg et al, Opt. Exp. 21 11257-11269 (2013). 3. A. Sridharan et al, Opt. Exp. 20 28792-28800 (2012). 4. D. Drachenberg et al, submitted to Opt. Express (2013). 5. M. Messerly et al, Opt. Exp. 21 12683-12698 (2013). 6. M. Messerly et al, Optics Letters 18 3329-3332 (2013). 7. P. Pax et al, submitted to Optics Letters (2013).
  14. 14. Lawrence Livermore National Laboratory LLNL-PRES-773886  We have the flexibility and motivation to work on “out of the box” designs that commercial vendors may be less interested in pursuing in early stage development  We bring a wide array of expertise to new fiber development and are very open about the manufacturing process and limitations  Do you have a problem where a novel optical fiber can help? 14
  15. 15. Lawrence Livermore National Laboratory LLNL-PRES-773886 15 Catherine Elizondo