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  1. Book ; Online ; Thesis: Laser power increase for GEO 600

    Affeldt, Christoph

    commissioning aspects towards an operation of GEO 600 at high laser power

    2014  

    Abstract: Gravitational wave detector, laser power increase, stray light. - Gravitationswellendetektor, Laserleistungserhöhung, ... ...

    Author's details von Christoph Affeldt
    Abstract Gravitational wave detector, laser power increase, stray light. - Gravitationswellendetektor, Laserleistungserhöhung, Streulicht
    Language English
    Size Online-Ressource (219 S., 9648 KB)
    Publisher Technische Informationsbibliothek u. Universitätsbibliothek
    Publishing place Hannover
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Hannover, 2014
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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  2. Book ; Online ; Thesis: Laser power increase for GEO 600

    Affeldt, Christoph

    commissioning aspects towards an operation of GEO 600 at high laser power

    2014  

    Abstract: Gravitational wave detector, laser power increase, stray light. - Gravitationswellendetektor, Laserleistungserhöhung, ... ...

    Author's details von Christoph Affeldt
    Abstract Gravitational wave detector, laser power increase, stray light. - Gravitationswellendetektor, Laserleistungserhöhung, Streulicht
    Language English
    Size Online-Ressource (219 S., 9648 KB)
    Publisher Technische Informationsbibliothek u. Universitätsbibliothek
    Publishing place Hannover
    Document type Book ; Online ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Hannover, 2014
    Database Former special subject collection: coastal and deep sea fishing

    Full text online

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    Inter-library loan at ZB MED

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  3. Book ; Thesis: Laser power increase for GEO 600

    Affeldt, Christoph

    commissioning aspects towards an operation of GEO 600 at high laser power

    2014  

    Abstract: Gravitational wave detector, laser power increase, stray light. - Gravitationswellendetektor, Laserleistungserhöhung, ... ...

    Author's details von Christoph Affeldt
    Abstract Gravitational wave detector, laser power increase, stray light. - Gravitationswellendetektor, Laserleistungserhöhung, Streulicht
    Language English
    Size XI, 201 S., Ill., graph. Darst.
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Univ., Diss.--Hannover, 2014
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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    Inter-library loan at ZB MED

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  4. Article ; Online: Characterization and evasion of backscattered light in the squeezed-light enhanced gravitational wave interferometer GEO 600.

    Bergamin, Fabio / Lough, James / Schreiber, Emil / Grote, Hartmut / Mehmet, Moritz / Vahlbruch, Henning / Affeldt, Christoph / Andric, Tomislav / Bisht, Aparna / Brinkmann, Marc / Kringel, Volker / Lück, Harald / Mukund, Nikhil / Nadji, Severin / Sorazu, Borja / Strain, Kenneth / Weinert, Michael / Danzmann, Karsten

    Optics express

    2023  Volume 31, Issue 23, Page(s) 38443–38456

    Abstract: Squeezed light is injected into the dark port of gravitational wave interferometers, in order to reduce the quantum noise. A fraction of the interferometer output light can reach the OPO due to sub-optimal isolation of the squeezing injection path. This ... ...

    Abstract Squeezed light is injected into the dark port of gravitational wave interferometers, in order to reduce the quantum noise. A fraction of the interferometer output light can reach the OPO due to sub-optimal isolation of the squeezing injection path. This backscattered light interacts with squeezed light generation process, introducing additional measurement noise. We present a theoretical description of the noise coupling mechanism and we prove the model with experimental results. We propose a control scheme to achieve a de-amplification of the backscattered light inside the OPO with a consequent reduction of the noise caused by it. The scheme was implemented at the GEO 600 detector and has proven to be crucial in maintaining a good level of quantum noise reduction of the interferometer for high parametric gain of the OPO. In particular, the mitigation of the backscattered light noise helped in reaching 6 dB of quantum noise reduction [Phys. Rev. Lett.126, 041102 (2021)10.1103/PhysRevLett.126.041102]. We show that the impact of backscattered-light-induced noise on the squeezing performance is phenomenologically equivalent to increased phase noise of the squeezing angle control. The results discussed in this paper provide a way for a more accurate estimation of the residual phase noise of the squeezed light field. Finally, the knowledge of the backscattered light noise coupling mechanism is a useful tool to inform the design of the squeezing injection path in terms of path stability and optical isolation.
    Language English
    Publishing date 2023-11-28
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.497555
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Matrix heater in the gravitational wave observatory GEO 600.

    Wittel, H / Affeldt, C / Bisht, A / Doravari, S / Grote, H / Lough, J / Lück, H / Schreiber, E / Strain, K A / Danzmann, K

    Optics express

    2018  Volume 26, Issue 18, Page(s) 22687–22697

    Abstract: Large scale laser interferometric gravitational wave detectors (GWDs), such as GEO 600 require high quality optics to reach their design sensitivity. The inevitable surface imperfections, inhomogeneities, and light-absorption induced thermal lensing in ... ...

    Abstract Large scale laser interferometric gravitational wave detectors (GWDs), such as GEO 600 require high quality optics to reach their design sensitivity. The inevitable surface imperfections, inhomogeneities, and light-absorption induced thermal lensing in the optics, can convert laser light from the fundamental mode to unwanted higher order modes, and pose challenges to the operation and sensitivity of the GWDs. Here we demonstrate the practical implementation of a thermal projection system which reduces those unwanted effects via targeted spatial heating of the optics. The thermal projector consists of 108 individually addressable heating elements which are imaged onto the beam splitter of GEO 600. We describe the optimization of the spatial heating profile and present the obtained results.
    Language English
    Publishing date 2018-09-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.26.022687
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Phase control of squeezed vacuum states of light in gravitational wave detectors.

    Dooley, K L / Schreiber, E / Vahlbruch, H / Affeldt, C / Leong, J R / Wittel, H / Grote, H

    Optics express

    2015  Volume 23, Issue 7, Page(s) 8235–8245

    Abstract: Quantum noise will be the dominant noise source for the advanced laser interferometric gravitational wave detectors currently under construction. Squeezing-enhanced laser interferometers have been recently demonstrated as a viable technique to reduce ... ...

    Abstract Quantum noise will be the dominant noise source for the advanced laser interferometric gravitational wave detectors currently under construction. Squeezing-enhanced laser interferometers have been recently demonstrated as a viable technique to reduce quantum noise. We propose two new methods of generating an error signal for matching the longitudinal phase of squeezed vacuum states of light to the phase of the laser interferometer output field. Both provide a superior signal to the one used in previous demonstrations of squeezing applied to a gravitational-wave detector. We demonstrate that the new signals are less sensitive to misalignments and higher order modes, and result in an improved stability of the squeezing level. The new signals also offer the potential of reducing the overall rms phase noise and optical losses, each of which would contribute to achieving a higher level of squeezing. The new error signals are a pivotal development towards realizing the goal of 6 dB and more of squeezing in advanced detectors and beyond.
    Language English
    Publishing date 2015-04-06
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.23.008235
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: First Demonstration of 6 dB Quantum Noise Reduction in a Kilometer Scale Gravitational Wave Observatory.

    Lough, James / Schreiber, Emil / Bergamin, Fabio / Grote, Hartmut / Mehmet, Moritz / Vahlbruch, Henning / Affeldt, Christoph / Brinkmann, Marc / Bisht, Aparna / Kringel, Volker / Lück, Harald / Mukund, Nikhil / Nadji, Severin / Sorazu, Borja / Strain, Kenneth / Weinert, Michael / Danzmann, Karsten

    Physical review letters

    2021  Volume 126, Issue 4, Page(s) 41102

    Abstract: Photon shot noise, arising from the quantum-mechanical nature of the light, currently limits the sensitivity of all the gravitational wave observatories at frequencies above one kilohertz. We report a successful application of squeezed vacuum states of ... ...

    Abstract Photon shot noise, arising from the quantum-mechanical nature of the light, currently limits the sensitivity of all the gravitational wave observatories at frequencies above one kilohertz. We report a successful application of squeezed vacuum states of light at the GEO 600 observatory and demonstrate for the first time a reduction of quantum noise up to 6.03±0.02  dB in a kilometer scale interferometer. This is equivalent at high frequencies to increasing the laser power circulating in the interferometer by a factor of 4. Achieving this milestone, a key goal for the upgrades of the advanced detectors required a better understanding of the noise sources and losses and implementation of robust control schemes to mitigate their contributions. In particular, we address the optical losses from beam propagation, phase noise from the squeezing ellipse, and backscattered light from the squeezed light source. The expertise gained from this work carried out at GEO 600 provides insight toward the implementation of 10 dB of squeezing envisioned for third-generation gravitational wave detectors.
    Language English
    Publishing date 2021-02-11
    Publishing country United States
    Document type Journal Article
    ZDB-ID 208853-8
    ISSN 1079-7114 ; 0031-9007
    ISSN (online) 1079-7114
    ISSN 0031-9007
    DOI 10.1103/PhysRevLett.126.041102
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Bonn / Germany

    Z 4' 58/153: Show issues

    Order via subito

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    Inter-library loan at ZB MED

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  8. Article ; Online: Alignment sensing and control for squeezed vacuum states of light.

    Schreiber, E / Dooley, K L / Vahlbruch, H / Affeldt, C / Bisht, A / Leong, J R / Lough, J / Prijatelj, M / Slutsky, J / Was, M / Wittel, H / Danzmann, K / Grote, H

    Optics express

    2016  Volume 24, Issue 1, Page(s) 146–152

    Abstract: Beam alignment is an important practical aspect of the application of squeezed states of light. Misalignments in the detection of squeezed light result in a reduction of the observable squeezing level. In the case of squeezed vacuum fields that contain ... ...

    Abstract Beam alignment is an important practical aspect of the application of squeezed states of light. Misalignments in the detection of squeezed light result in a reduction of the observable squeezing level. In the case of squeezed vacuum fields that contain only very few photons, special measures must be taken in order to sense and control the alignment of the essentially dark beam. The GEO 600 gravitational wave detector employs a squeezed vacuum source to improve its detection sensitivity beyond the limits set by classical quantum shot noise. Here, we present our design and implementation of an alignment sensing and control scheme that ensures continuous optimal alignment of the squeezed vacuum field at GEO 600 on long time scales in the presence of free-swinging optics. This first demonstration of a squeezed light automatic alignment system will be of particular interest for future long-term applications of squeezed vacuum states of light.
    Language English
    Publishing date 2016-01-11
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.24.000146
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Direct limits for scalar field dark matter from a gravitational-wave detector.

    Vermeulen, Sander M / Relton, Philip / Grote, Hartmut / Raymond, Vivien / Affeldt, Christoph / Bergamin, Fabio / Bisht, Aparna / Brinkmann, Marc / Danzmann, Karsten / Doravari, Suresh / Kringel, Volker / Lough, James / Lück, Harald / Mehmet, Moritz / Mukund, Nikhil / Nadji, Séverin / Schreiber, Emil / Sorazu, Borja / Strain, Kenneth A /
    Vahlbruch, Henning / Weinert, Michael / Willke, Benno / Wittel, Holger

    Nature

    2021  Volume 600, Issue 7889, Page(s) 424–428

    Abstract: The nature of dark matter remains unknown to date, although several candidate particles are being considered in a dynamically changing research ... ...

    Abstract The nature of dark matter remains unknown to date, although several candidate particles are being considered in a dynamically changing research landscape
    Language English
    Publishing date 2021-12-15
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 120714-3
    ISSN 1476-4687 ; 0028-0836
    ISSN (online) 1476-4687
    ISSN 0028-0836
    DOI 10.1038/s41586-021-04031-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 26: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)
    Zs.MG 9: Show issues
    Zs.MO 244: Show issues

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  10. Article ; Online: High power and ultra-low-noise photodetector for squeezed-light enhanced gravitational wave detectors.

    Grote, Hartmut / Weinert, Michael / Adhikari, Rana X / Affeldt, Christoph / Kringel, Volker / Leong, Jonathan / Lough, James / Lück, Harald / Schreiber, Emil / Strain, Kenneth A / Vahlbruch, Henning / Wittel, Holger

    Optics express

    2016  Volume 24, Issue 18, Page(s) 20107–20118

    Abstract: Current laser-interferometric gravitational wave detectors employ a self-homodyne readout scheme where a comparatively large light power (5-50 mW) is detected per photosensitive element. For best sensitivity to gravitational waves, signal levels as low ... ...

    Abstract Current laser-interferometric gravitational wave detectors employ a self-homodyne readout scheme where a comparatively large light power (5-50 mW) is detected per photosensitive element. For best sensitivity to gravitational waves, signal levels as low as the quantum shot noise have to be measured as accurately as possible. The electronic noise of the detection circuit can produce a relevant limit to this accuracy, in particular when squeezed states of light are used to reduce the quantum noise. We present a new electronic circuit design reducing the electronic noise of the photodetection circuit in the audio band. In the application of this circuit at the gravitational-wave detector GEO 600 the shot-noise to electronic noise ratio was permanently improved by a factor of more than 4 above 1 kHz, while the dynamic range was improved by a factor of 7. The noise equivalent photocurrent of the implemented photodetector and circuit is about 5μA/Hz above 1 kHz with a maximum detectable photocurrent of 20 mA. With the new circuit, the observed squeezing level in GEO 600 increased by 0.2 dB. The new circuit also creates headroom for higher laser power and more squeezing to be observed in the future in GEO 600 and is applicable to other optics experiments.
    Language English
    Publishing date 2016-09-05
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.24.020107
    Database MEDical Literature Analysis and Retrieval System OnLINE

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