Global Security 2009

Optical Fiber Fabrication at LLNLDr. Jay W. Dawson, Fiber Technologies Group Leader

LLNL-PRES-773886This 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

Lawrence Livermore National Laboratory LLNL-PRES-773886Optical fibers and fiber lasers have many advantageous properties 2

FibersDiffraction limited beamsRobust, flexible transportOperate in extreme environments and insensitive to electro-magnetic interferenceFiber LasersLow maintenance & high reliability Efficient (>30% wall-plug)High average powers (kW)

Lawrence Livermore National Laboratory LLNL-PRES-773886These properties make optical fibers enabling for many industrial applications 3

Telecom

Flexible Delivery for Industrial Machining

High Power Laser Sources

Distributed SensorsShort-pulse surgery laser delivery

Sensors for Oil and Gas

High Voltage Current SensorsThese are examples of a wide array of potential applications in flexible light transport, sensors and components for laser systems.

Lawrence Livermore National Laboratory LLNL-PRES-773886Optical fibers were originally developed for the telecom industry 4

Cross section: 125 m O.D.Very low losses attainableStrong and Flexible50% transmission over 30km

Lawrence Livermore National Laboratory LLNL-PRES-773886New fabrication techniques open the design space enabling new possibilities 5

Diffraction

Photonic crystal fiber

Refraction

Conventional fiber

Lawrence Livermore National Laboratory LLNL-PRES-773886A dedicated R&D facility permits greater risk-taking in fiber design 6

Optical Near FieldOptical Far Field

250 m200 m

10 m X 120 mYb3+ Slab WaveguideSecondary Waveguide for Diode Pump Light

5 W at 44% optical efficiencyExample: investigation of rectangular core fiber lasers for improved power scaling

Lawrence Livermore National Laboratory LLNL-PRES-773886Finite element modeling was used to design a ribbon fiber waveguide 7

Proposed DesignCalculated Waveguide Modes

Lawrence Livermore National Laboratory LLNL-PRES-773886The computer model was turned into a manufacturing design 8

Computer ModelManufacturing Design

Lawrence Livermore National Laboratory LLNL-PRES-773886We then used the stack and draw process to fabricate the optical fiber 9

Raw MaterialDraw to ~1mm rods and tubesStack to Fiber DesignFinal Preform in FurnaceFiber ProductionDraw Tower

Lawrence Livermore National Laboratory LLNL-PRES-773886The fiber was tested against the original computer models 10

Lawrence Livermore National Laboratory LLNL-PRES-773886We have fabricated a number of fiber designs since commissioning in 2012 11

215 m

100 mPassive Ribbon Fiber

200 m

250 m10 m X 120 mYb3+ Ribbon Fiber

250 mUV Rad HardQualification Fiber

Hollow Core Cane (preform)

Negative Curvature Core for mid-IR

Lawrence Livermore National Laboratory LLNL-PRES-773886Hollow core waveguides for high power transportShort wavelength fiber lasers (