Showing papers by "Karsten Danzmann published in 2006"
TL;DR: A coherent control scheme for stable phase locking of squeezed vacuum fields at sideband fields at frequencies from 10 Hz to 10 kHz, which is a frequency regime of particular interest in gravitational-wave detection and for which conventional control schemes have failed so far.
Abstract: We propose and demonstrate a coherent control scheme for stable phase locking of squeezed vacuum fields. We focus on sideband fields at frequencies from 10 Hz to 10 kHz, which is a frequency regime of particular interest in gravitational-wave detection and for which conventional control schemes have failed so far. A vacuum field with broadband squeezing covering this entire band was produced using optical parametric oscillation and characterized with balanced homodyne detection. The system was stably controlled over long periods utilizing two coherent but frequency shifted control fields. In order to demonstrate the performance of our setup the squeezed field was used for a nonclassical sensitivity improvement of a Michelson interferometer at audio frequencies.
198 citations
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TL;DR: The GEO-HF project as mentioned in this paper is a project to improve the sensitivity of the GEO detector by small sequential upgrades some of which will be tested in prototypes first, and the development, test and installation of these upgrades are named as the "Geo-HF Project."
Abstract: The GEO 600 gravitational wave detector uses advanced technologies including signal recycling and monolithic fused-silica suspensions to achieve a sensitivity close to the kilometre scale LIGO and VIRGO detectors. As soon as the design sensitivity of GEO 600 is reached, the detector will be operated as part of the worldwide network to acquire data of scientific interest. The limited infrastructure at the GEO site does not allow for a major upgrade of the detector. Hence the GEO collaboration decided to improve the sensitivity of the GEO detector by small sequential upgrades some of which will be tested in prototypes first. The development, test and installation of these upgrades are named 'The GEO-HF Project.' This paper describes the upgrades considered in the GEO-HF project as well as their scientific reasons. We will describe the changes in the GEO 600 infrastructure and the prototype work that is planned to support these upgrades. Finally, we will point to some laboratory research that identifies new technologies or optical configurations that might undergo a transition into detector subsystems within the GEO-HF project.
153 citations
TL;DR: The German/British project GEO600 achieved an instrumental duty cycle of 97% with a peak sensitivity of 7 × 10−22 Hz−1/2 at 1 kHz.
Abstract: Of all the large interferometric gravitational-wave detectors, the German/British project GEO600 is the only one which uses dual recycling. During the four weeks of the international S4 data-taking run it reached an instrumental duty cycle of 97% with a peak sensitivity of 7 × 10−22 Hz−1/2 at 1 kHz. This paper describes the status during S4 and improvements thereafter.
135 citations
TL;DR: In this paper, a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers was reported. But no events that could be identified as gravitational waves in the 385.6 hours of data that they searched.
Abstract: We report on a search for gravitational waves from binary black hole inspirals in the data from the second science run of the LIGO interferometers. The search focused on binary systems with component masses between 3 and 20M⊙. Optimally oriented binaries with distances up to 1 Mpc could be detected with efficiency of at least 90%. We found no events that could be identified as gravitational waves in the 385.6 hours of data that we searched.
87 citations
TL;DR: The achieved stability level of a Nd:YAG laser in the frequency band from 1 Hz to 100 kHz is close to the requirements for the Advanced LIGO gravitational wave detector.
Abstract: We present results on the power stabilization of a Nd:YAG laser in the frequency band from 1 Hz to 100 kHz. High-power, low-noise photodetectors are used in a dc-coupled control loop to achieve relative power fluctuations down to 5×10−9 Hz−1/2 at 10 Hz and 3.5×10−9 Hz−1/2 up to several kHz, which is very close to the shot-noise limit for 80 mA of detected photocurrent on each detector. We investigated and eliminated several noise sources such as ground loops and beam pointing. The achieved stability level is close to the requirements for the Advanced LIGO gravitational wave detector.
50 citations
TL;DR: In this paper, an optical characterization of an ultrahigh diffraction efficiency grating in a first-order Littrow configuration was reported, and the measurement of the cavity finesse provided precise information about the grating efficiency and its optical loss.
Abstract: We report on the optical characterization of an ultrahigh diffraction efficiency grating in a first-order Littrow configuration. The apparatus used was an optical cavity built from the grating under investigation and an additional high-reflection mirror. The measurement of the cavity finesse provided precise information about the grating’s diffraction efficiency and its optical loss. We measured a finesse of 1580 from which we deduced a diffraction efficiency of 99.635 0.016% and an overall optical loss due to scattering and absorption of just 0.185%. Such high-quality gratings, including the tool used for their characterization, might apply for future gravitational wave detectors. For example, the demonstrated cavity itself presents an all-reflective, low-loss Fabry‐Perot resonator that might replace conventional arm cavities in advanced high-power Michelson interferometers. © 2006 Optical Society of America OCIS codes: 050.1950, 230.1360, 120.2230.
49 citations
TL;DR: In this paper, a thin single-layer grating waveguide structure was proposed for high reflectivity, but low thermal noise, alternative to conventional coatings for gravitational wave detector test mass mirrors.
Abstract: We propose thin single-layer grating waveguide structures to be used as high reflectivity, but low thermal noise, alternative to conventional coatings for gravitational wave detector test mass mirrors. Grating waveguide (GWG) coatings can show a reflectivity of up to 100% with an overall thickness of less than a wavelength. We theoretically investigate GWG coatings for 1064 nm based on tantala (Ta2O5) on a silica substrate focusing on broad spectral response and low thickness.
47 citations
TL;DR: In this article, the authors search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003 using a simple trigger exchange method.
Abstract: We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an intercollaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3M⊙ of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in future network inspiral analyses.
45 citations
TL;DR: In this paper, the LISA Technology Package uses a heterodyne Mach-Zehnder interferometer to monitor the relative motion of the test masses with picometer accuracy.
Abstract: The LISA Technology Package uses a heterodyne Mach–Zehnder interferometer to monitor the relative motion of the test masses with picometer accuracy. This paper discusses two classes of noise sources that were identified and investigated during the prototype experiments. Most troublesome are electrically induced sidebands on the light, which give rise to nonlinearities in the interferometer output. Even worse, if the differential pathlength between two optical fibres fluctuates, a noise term of milliradian amplitude appears and completely spoils the performance. We discuss the origin and mitigation of this process. Dissimilar beam shapes of the interfering beams produce another type of noise in conjunction with beam jitter and spatially inhomogeneous photodetectors. To study and minimize this effect, we have built a real-time high-resolution phasefront imaging system that will be used for the production of the flight model.
44 citations
TL;DR: In this paper, a search for gravitational-wave bursts in data from the three LIGO interferometric detectors during their third science run was reported. But no gravitational-warp signals were detected in the eight days of analysed data.
Abstract: We report on a search for gravitational-wave bursts in data from the three LIGO interferometric detectors during their third science run. The search targets sub-second bursts in the frequency range 100–1100 Hz for which no waveform model is assumed and has a sensitivity in terms of the root-sum-square (rss) strain amplitude of hrss ~ 10−20 Hz−1/2. No gravitational-wave signals were detected in the eight days of analysed data.
43 citations
TL;DR: LISA, the Laser Interferometer Space Antenna, will be launched by NASA and ESA in the 2014 timeframe and will be the first gravitational wave observatory for the many fascinating sources at low frequencies (down to 10−5 Hz) as mentioned in this paper.
Abstract: LISA, the Laser Interferometer Space Antenna, will be launched by NASA and ESA in the 2014 timeframe and will be the first gravitational wave observatory for the many fascinating sources at low frequencies (down to 10−5 Hz). One of the challenges is to perform precision laser interferometry over a distance of 5 million km. This paper describes recent developments in the interferometer design.
TL;DR: In this paper, the authors derive generic phase and amplitude coupling relations for beam splitters-combiners that couple a single port with three output ports or input ports, respectively, and apply the coupling relations to a reflection grating that serves as a coupler to a single-ended Fabry-Perot ring cavity.
Abstract: We derive generic phase and amplitude coupling relations for beam splitters-combiners that couple a single port with three output ports or input ports, respectively. We apply the coupling relations to a reflection grating that serves as a coupler to a single-ended Fabry-Perot ring cavity. In the impedance-matched case such an interferometer can act as an all-reflective ring mode cleaner. It is further shown that in the highly undercoupled case almost complete separation of carrier power and phase signal from a cavity strain can be achieved.
TL;DR: A sensitive method is developed to measure the absorption inside the beam splitter of the GEO 600, taking advantage of the effect of thermal lensing and derived a bulk absorption of less than 0.25 ppm/cm, which is the lowest value of light absorption inside fused silica reported so far in the literature.
Abstract: Low-absorption optics made of OH-reduced fused silica are a key technology for future gravitational wave detectors such as the Advanced LIGO. We developed a sensitive method to measure the absorption inside the beam splitter of the GEO 600, taking advantage of the effect of thermal lensing. Using this method, we derived a bulk absorption of less than 0.25 ppm/cm for a piece of Suprasil 311 SV at a wavelength of 1064 nm. To the best of our knowledge, this is the lowest value of light absorption inside fused silica reported so far in the literature.
TL;DR: In this article, an amplitude modulated laser diode with up to 1.4 W output power at a wavelength of 1035 nm was used to calibrate the GEO 600 detector.
02 Mar 2006
TL;DR: In this paper, the status of the LISA technology package (LTP) is discussed and the dominant noise source in the interferometer prototype has been investigated and improved such that it is now comfortably below its budget at all frequencies.
Abstract: This paper gives an update on the status of the LISA technology package (LTP) which is to be launched in 2009 by ESA as a technology demonstration mission for the space- borne gravitational wave observatory LISA. The dominant noise source in the interferometer prototype has been investigated and improved such that it is now comfortably below its budget at all frequencies.
08 Dec 2006
TL;DR: In this paper, the authors present the status of their work concerning the design and implementation of a LISA-like PMS with particular emphasis on the hardware development based on Field Programmable Gate Arrays (FPGA) as the main technology platform.
Abstract: The baseline concept of LISA had been developed within an industrial investigation by Astrium/EADS and is being reviewed since 2005 in an ongoing formulation phase. One of the most important key technology development issues remains the demonstration of the interferometric readout of the main science measurement. This includes the hardware development of an appropriate Phase Measurement System (PMS). We present the status of our work concerning the design and implementation of a LISA‐like PMS with particular emphasis on the hardware development based on Field Programmable Gate Arrays (FPGA’s) as main technology platform and we report on our first results demonstrating the performance of the PMS with synthetic signals.
TL;DR: In this article, the authors present methods of noise analysis that were developed and utilized for the commissioning of the GEO 600 detector, and the focal point of this method is a technique called noise projection that is used to determine the levels of contribution of various noise sources to the detector output.
Abstract: An international network of interferometric gravitational-wave detectors is now in operation, and has entered a period of intense commissioning focused on bringing the instruments to their theoretical sensitivity limits. To expedite this process, noise analysis techniques have been developed by the groups associated with each instrument. We present methods of noise analysis that were developed and utilized for the commissioning of the GEO 600 detector. The focal point of this paper is a technique called noise projection that is used to determine the levels of contribution of various noise sources to the detector output. Example applications of this method to control loops typical of those employed in an interferometric GW detector are presented. Possible extensions of noise projections, including technical noise subtraction and gravitational-wave vetoes are also discussed.
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TL;DR: In this article, the authors present the first experimental confirmation of self-phaselocked delay interferometry, which consists in comparing the prompt laser signal with a delayed version of itself that has been reflected in another LISA satellite 5 million km away.
Abstract: We present the first experimental confirmation of the so-called "self-phaselocked delay interferometry". This laser frequency stabilization technique consists basically in comparing the prompt laser signal with a delayed version of itself that has been reflected in another LISA satellite 5 million km away. In our table-top experiment, the phase of a voltage-controlled oscillator is stabilized by means of a control loop based on this technique. In agreement with the theory, the measured unity gain frequency is not limited by the inverse of the used delay (1.6 microseconds). In the time domain, the system also behaves as predicted, including the appearance of a quasi-periodic "ringing" just after the lock acquisition, which decays exponentially. Its initial amplitude is smaller when the loop gain is slowly ramped up instead of suddenly switched on.
TL;DR: Using the gratings as couplers to Fabry-Perot cavities, the results of an earlier theoretical description of the phases at a three-port grating are validated.
Abstract: We experimentally demonstrate the phase relations of three-port gratings by investigating three-port coupled Fabry-Perot cavities. Two different gratings that have the same first-order diffraction efficiency but differ substantially in their second-order diffraction efficiency have been designed and manufactured. Using the gratings as couplers to Fabry-Perot cavities, we could validate the results of an earlier theoretical description of the phases at a three-port grating [Opt. Lett. 30, 1183 (2005)]
TL;DR: In a recent table-top experiment, the authors demonstrated the compatibility of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal recycling and squeezed-field injection.
Abstract: In a recent table-top experiment, we demonstrated the compatibility of three advanced interferometer techniques for gravitational wave detection, namely power-recycling, detuned signal recycling and squeezed-field injection. The interferometer's signal-to-noise ratio was improved by up to 2.8 dB beyond the coherent state's shot-noise. This value was mainly limited by optical losses on the squeezed field. We present a detailed analysis of the optical losses in our experiment and provide an estimation of the possible nonclassical performance of a future squeezed-field enhanced GEO 600 detector.
TL;DR: The optical properties of a caesium atomic beam driven on a resonant hyperfine transition in the D(2) line were studied as a function of the probe laser frequency using a third off-resonant laser system.
02 Mar 2006
TL;DR: In this paper, the authors discuss possible setups to achieve high laser power and describe a 200 W prestabilized laser system (PSL) with very low temporal and spatial fluctuations.
Abstract: Second generation gravitational wave detectors require high power lasers with several 100 W of output power and with very low temporal and spatial fluctuations. In this paper we discuss possible setups to achieve high laser power and describe a 200 W prestabilized laser system (PSL). The PSL noise requirements for advanced gravitational wave detectors will be discussed in general and the stabilization scheme proposed for the Advanced LIGO PSL will be described. Special emphasis will be given to the most demanding power stabilization requiremets and new results (RIN ≤ 4×10 −9 / √ Hz) will be presented.
TL;DR: In this article, a procedure to perform fully autonomous on-orbit alignment of the interferometer on board the LISA Technology Package (LTP) has been presented, which consists of two free-floating test masses as inertial sensors that additionally serve as end mirrors of a set of interferometers.
Abstract: This paper presents a procedure to perform fully autonomous on-orbit alignment of the interferometer on board the LISA Technology Package (LTP). LTP comprises two free-floating test masses as inertial sensors that additionally serve as end mirrors of a set of interferometers. From the output signals of the interferometers, a subset has been selected to obtain alignment information of the test masses. Based on these signals, an alignment procedure was developed and successfully tested on the engineering model of the optical bench. Furthermore, operation procedures for the characterization of critical on-orbit properties of the optical metrology system (e.g. fibre noise) have been established.
TL;DR: In this paper, pump light intensity stabilisation of a single-mode laser diode pumped Nd:YAG non-planar ring oscillator (NPRO) was shown to achieve significant intensity noise reduction and frequency noise suppression in the same order of magnitude.
Abstract: We have shown that pump light intensity stabilisation of a single-mode laser diode pumped Nd:YAG non-planar ring oscillator (NPRO) results in significant intensity noise reduction of the NPRO, as well as frequency noise suppression in the same order of magnitude. This effect does not occur in conventional laser diode array pumped NPROs due to mode beating effects originating in the multi-mode pump. As opposed to individual intensity and frequency stabilisation, pump light stabilisation contributes a simplified stabilisation scheme for single-mode laser diode pumped NPROs for high precision applications.
29 Jan 2006
TL;DR: In this article, the current status of suitable solid-state laser sources in the field of gravitational wave detection is presented, with a single-frequency operation with output power levels up to 200W.
Abstract: In the field of gravitational wave detection linearly polarized fundamental mode laser sources in single-frequency operation with output power levels up to 200W are required. The current status of suitable solid-state lasers will be presented.
TL;DR: In this paper, the LISA requirement of relative power noise below 2 × 10 −4 /Hz 1/2 was fulfilled in the whole frequency range from 0.1 mHz to 1 Hz.
Abstract: The two most promising configurations for the LISA laser are a stand-alone diode-pumped nonplanar ring oscillator (NPRO) or a fibre amplifier seeded by a low-power NPRO. The stand-alone laser was stabilized in frequency to a ULE cavity and in power to an electronic reference. For the first time the LISA requirement of relative power noise below 2 × 10 −4 /Hz 1/2 was fulfilled in the whole frequency range from 0.1 mHz to 1 Hz. The LISA goal of frequency noise below 30 Hz/Hz 1/2 was achieved for frequencies above 3 mHz. As a first step in the characterization of an oscillator-amplifier system, the excess frequency noise of an ytterbium-doped fibre amplifier was measured. For frequencies between 0.1 mHz and 1 Hz the excess noise was measured to be below 0.1 Hz/Hz 1/2 , which is significantly below the free-running frequency
02 Mar 2006
TL;DR: In this article, an all-reflective Fabry-Perot interferometer concept in 2nd order Littrow mount is investigated and the input-output relations for such a resonator are derived treating the grating coupler by means of a scattering matrix formalism.
Abstract: All-reflective interferometry based on nano-structured diffraction gratings offers new possibilities for gravitational wave detection. We investigate an all-reflective Fabry-Perot interferometer concept in 2nd order Littrow mount. The input-output relations for such a resonator are derived treating the grating coupler by means of a scattering matrix formalism. A low loss dielectric reflection grating has been designed and manufactured to test the properties of such a grating cavity.
08 Dec 2006
TL;DR: In this paper, an athermal glass that should minimize the thermally induced pathlength changes was selected to minimize the pathlength sensitivity to both temperature fluctuations and temperature gradients has been measured with a dedicated interferometer prototype.
Abstract: In LISA Pathfinder and LISA the position fluctuations of drag free test masses will be determined interferometrically to picometer precision. To this end, laser light is brought to interference on an ultra stable optical bench after being reflected on the test mass, which needs to be in an ultra‐high vacuum. The present baseline for both missions includes a separate vacuum enclosure for each test mass, so that the sensing laser beam has to pass through an optical window. This window is therefore a transmissive element in the interferometer and its associated pathlength fluctuations are potentially significant. We have selected an athermal glass that should minimize the thermally induced pathlength changes.Several prototype windows, both mounted and unmounted, have been produced and characterized. The pathlength sensitivity to both temperature fluctuations and temperature gradients has been measured with a dedicated interferometer prototype. We have also compared the long‐term stability of the LISA Technol...
01 Jan 2006
TL;DR: The LIGO interferometers are operating as gravitational wave observatories, with a noise level near an order of magnitude of the goal and the first scientific data recently taken as mentioned in this paper.
Abstract: The LIGO interferometers are operating as gravitational wave observatories, with a noise level near an order of magnitude of the goal and the first scientific data recently taken. This data has been analyzed for four different categories of gravitational wave sources; millisecond bursts, inspiralling binary neutron stars, periodic waves from a known pulsar, and stochastic background. Research and development is also underway for the next generation LIGO detector, Advanced LIGO.
21 May 2006
TL;DR: In this article, a diode laser concept for precision spectroscopy is presented based on a novel optical feedback scheme that combines excellent frequency stability (< 35 kHz line width in 290 ms) with good tuneability (45 GHz continuously, 50 nm overall).
Abstract: We present a diode laser concept for precision spectroscopy which is based on a novel optical feedback scheme that combines excellent frequency stability (< 35 kHz line width in 290 ms) with good tuneability (45 GHz continuously, 50 nm overall).