Tabletop investigation of parametric instability and light scattering phenomena in gravitational wave detectors

    Research output: ThesisDoctoral Thesis

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    Abstract

    [Truncated] Parametric instability is a potential threat to the operation of advanced gravitational wave detectors. It arises from three-mode parametric interactions between the test mass acoustic modes and the optical modes, mediated by the radiation pressure force.

    This thesis describes experiments to observe and characterise three-mode parametric instability on a table-top setup. The setup consists of a 50 nm thick silicon nitride membrane, with a high Q factor (106 at 1.7 MHz), placed in the middle of a 10 cm Fabry-P´erot optical cavity. This configuration allows tuning of the cavity to achieve parametric interactions. The cavity was tuned until the injected optical mode and the scattered optical mode were resonant in the cavity, and were thus enhanced by cavity resonance. High circulating power per unit mass was achieved by using mirrors with highly reflective coatings and a low mass resonator.

    I observed the mechanical mode ring-up when the input power is above the instability threshold. The ring-up rate agrees with previous model predictions. Contrary to expectations, I observed power saturation of the mechanical amplitude, and parametric instability does not lead to loss of cavity lock. This facilitates the implementation of control techniques in advanced gravitational wave detectors. This is the first observation of three-mode parametric instability in a free-space Fabry-P´erot cavity.

    Because previous models do not describe the power saturation of the mechanical amplitude, a large amplitude model was developed to describe three-mode parametric instability. The experimental results are consistent with this model, which predicts exponential growth of the mechanical oscillation, followed by saturation.

    A scheme of acoustic feedback is designed for controlling the parametric interaction. Theoretical analysis shows that this feedback is able to introduce damping in the mechanical mode. Heating and cooling of the mechanical mode was demonstrated by applying feedback with appropriate phase.

    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2014

    Fingerprint

    gravitational waves
    light scattering
    detectors
    scattering
    cavities
    saturation
    Q factors
    acoustics
    theses
    rings
    radiation pressure
    interactions
    silicon nitrides
    damping
    resonators
    tuning
    mirrors
    membranes
    cooling
    coatings

    Cite this

    @phdthesis{567bfd651a0f4efa8af29912d451bbd6,
    title = "Tabletop investigation of parametric instability and light scattering phenomena in gravitational wave detectors",
    abstract = "[Truncated] Parametric instability is a potential threat to the operation of advanced gravitational wave detectors. It arises from three-mode parametric interactions between the test mass acoustic modes and the optical modes, mediated by the radiation pressure force. This thesis describes experiments to observe and characterise three-mode parametric instability on a table-top setup. The setup consists of a 50 nm thick silicon nitride membrane, with a high Q factor (106 at 1.7 MHz), placed in the middle of a 10 cm Fabry-P´erot optical cavity. This configuration allows tuning of the cavity to achieve parametric interactions. The cavity was tuned until the injected optical mode and the scattered optical mode were resonant in the cavity, and were thus enhanced by cavity resonance. High circulating power per unit mass was achieved by using mirrors with highly reflective coatings and a low mass resonator. I observed the mechanical mode ring-up when the input power is above the instability threshold. The ring-up rate agrees with previous model predictions. Contrary to expectations, I observed power saturation of the mechanical amplitude, and parametric instability does not lead to loss of cavity lock. This facilitates the implementation of control techniques in advanced gravitational wave detectors. This is the first observation of three-mode parametric instability in a free-space Fabry-P´erot cavity. Because previous models do not describe the power saturation of the mechanical amplitude, a large amplitude model was developed to describe three-mode parametric instability. The experimental results are consistent with this model, which predicts exponential growth of the mechanical oscillation, followed by saturation. A scheme of acoustic feedback is designed for controlling the parametric interaction. Theoretical analysis shows that this feedback is able to introduce damping in the mechanical mode. Heating and cooling of the mechanical mode was demonstrated by applying feedback with appropriate phase.",
    keywords = "Opto-mechanics, 3-mode interaction, Parametric instabilities, Rayleigh scattering, Feedback control, SiN membrane, Fused silica test mass",
    author = "Xu Chen",
    year = "2014",
    language = "English",

    }

    TY - THES

    T1 - Tabletop investigation of parametric instability and light scattering phenomena in gravitational wave detectors

    AU - Chen, Xu

    PY - 2014

    Y1 - 2014

    N2 - [Truncated] Parametric instability is a potential threat to the operation of advanced gravitational wave detectors. It arises from three-mode parametric interactions between the test mass acoustic modes and the optical modes, mediated by the radiation pressure force. This thesis describes experiments to observe and characterise three-mode parametric instability on a table-top setup. The setup consists of a 50 nm thick silicon nitride membrane, with a high Q factor (106 at 1.7 MHz), placed in the middle of a 10 cm Fabry-P´erot optical cavity. This configuration allows tuning of the cavity to achieve parametric interactions. The cavity was tuned until the injected optical mode and the scattered optical mode were resonant in the cavity, and were thus enhanced by cavity resonance. High circulating power per unit mass was achieved by using mirrors with highly reflective coatings and a low mass resonator. I observed the mechanical mode ring-up when the input power is above the instability threshold. The ring-up rate agrees with previous model predictions. Contrary to expectations, I observed power saturation of the mechanical amplitude, and parametric instability does not lead to loss of cavity lock. This facilitates the implementation of control techniques in advanced gravitational wave detectors. This is the first observation of three-mode parametric instability in a free-space Fabry-P´erot cavity. Because previous models do not describe the power saturation of the mechanical amplitude, a large amplitude model was developed to describe three-mode parametric instability. The experimental results are consistent with this model, which predicts exponential growth of the mechanical oscillation, followed by saturation. A scheme of acoustic feedback is designed for controlling the parametric interaction. Theoretical analysis shows that this feedback is able to introduce damping in the mechanical mode. Heating and cooling of the mechanical mode was demonstrated by applying feedback with appropriate phase.

    AB - [Truncated] Parametric instability is a potential threat to the operation of advanced gravitational wave detectors. It arises from three-mode parametric interactions between the test mass acoustic modes and the optical modes, mediated by the radiation pressure force. This thesis describes experiments to observe and characterise three-mode parametric instability on a table-top setup. The setup consists of a 50 nm thick silicon nitride membrane, with a high Q factor (106 at 1.7 MHz), placed in the middle of a 10 cm Fabry-P´erot optical cavity. This configuration allows tuning of the cavity to achieve parametric interactions. The cavity was tuned until the injected optical mode and the scattered optical mode were resonant in the cavity, and were thus enhanced by cavity resonance. High circulating power per unit mass was achieved by using mirrors with highly reflective coatings and a low mass resonator. I observed the mechanical mode ring-up when the input power is above the instability threshold. The ring-up rate agrees with previous model predictions. Contrary to expectations, I observed power saturation of the mechanical amplitude, and parametric instability does not lead to loss of cavity lock. This facilitates the implementation of control techniques in advanced gravitational wave detectors. This is the first observation of three-mode parametric instability in a free-space Fabry-P´erot cavity. Because previous models do not describe the power saturation of the mechanical amplitude, a large amplitude model was developed to describe three-mode parametric instability. The experimental results are consistent with this model, which predicts exponential growth of the mechanical oscillation, followed by saturation. A scheme of acoustic feedback is designed for controlling the parametric interaction. Theoretical analysis shows that this feedback is able to introduce damping in the mechanical mode. Heating and cooling of the mechanical mode was demonstrated by applying feedback with appropriate phase.

    KW - Opto-mechanics

    KW - 3-mode interaction

    KW - Parametric instabilities

    KW - Rayleigh scattering

    KW - Feedback control

    KW - SiN membrane

    KW - Fused silica test mass

    M3 - Doctoral Thesis

    ER -