Low loss amorphous Ta<sub>2</sub>O<sub>5</sub> coatings grown by reactive sputtering for dielectric mirrors used for gravitational wave detection

ORAL

Abstract

The ability of LIGO and others in the gravitational wave community to detect astronomical events relies on the quality of optical mirrors used in interferometers. A lot of effort is devoted to reduce optical absorption and mechanical loss in the layers that make up the mirror coatings. Amorphous tantala is of interest as the high index of refraction layer but contributes the most to overall mechanical loss. The mechanisms that lead to mechanical loss must be understood in order to minimize the losses.

Amorphous tantala 500nm films are deposited using reactive sputtering of a tantalum target where growth temperatures are varied from room temperature to 600C. Thermally activated and tunneling mechanisms both contribute to the overall mechanical loss which can be measured through internal friction techniques. The thermally activated are measured at room temperature using Gentle Nodal Suspension and the tunneling are measured at temperatures below 10K using Double Paddle Oscillators. These results provide a deeper understanding of the energy dissipation in amorphous tantala due to both tunneling and thermally activated loss mechanisms.

*Gordon and Betty Moore Foundation

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Presenters

  • Keerti Shukla

    • Materials Science and Engineering, UC Berkeley

Authors

  • Keerti Shukla

    • Materials Science and Engineering, UC Berkeley

  • Manel Molina-Ruiz

    • Physics, UC Berkeley

  • Matt Abernathy

    • United States Naval Research Laboratory

  • Alena Ananyeva

    • LIGO Laboratory, California Institute of Technology, Pasadena, CA, USA
    • California Institute of Technology
    • LIGO Laboratory, California Institute of Technology

  • Riccardo Bassiri

    • Department of Applied Physics, Ginzton Laboratory, Stanford University, Stanford, CA, USA
    • Applied Physics, Stanford University
    • E. L. Ginzton Laboratory, Stanford University
    • Ginzton Laboratory, Stanford University
    • E. L. Ginzton Laboratory, Stanford

  • Martin Fejer

    • Department of Applied Physics, Ginzton Laboratory, Stanford University, Stanford, CA, USA
    • Stanford University
    • Applied Physics, Stanford University
    • E. L. Ginzton Laboratory, Stanford University
    • Ginzton Laboratory, Stanford University
    • E. L. Ginzton Laboratory, Stanford

  • Eric Keith Gustafson

    • LIGO Laboratory, California Institute of Technology, Pasadena, CA, USA
    • California Institute of Technology
    • LIGO Laboratory, California Institute of Technology
    • LIGO Lab, California Institute of Technology

  • Xiao Liu

    • United States Naval Research Laboratory
    • Code 7130, Naval Research Laboratory, Washington, DC
    • US Naval Research Laboratory

  • Ashot Markosyan

    • Department of Applied Physics, Ginzton Laboratory, Stanford University, Stanford, CA, USA
    • Stanford University
    • Edward L. Ginzton Laboratory, Stanford University

  • Thomas Metcalf

    • United States Naval Research Laboratory
    • Code 7130, Naval Research Laboratory, Washington, DC

  • Gabriele Vajente

    • LIGO Laboratory, California Institute of Technology, Pasadena, CA, USA
    • LIGO Laboratory, California Institute of Technology

  • Frances Hellman

    • Physics and Materials Science and Engineering, UC Berkeley
    • Physics, University of California, Berkeley
    • University of California, Berkeley
    • Department of Physics, University of California, Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory