381 research outputs found
Coating thermal noise for arbitrary shaped beams
Advanced LIGO's sensitivity will be limited by coating noise. Though this
noise depends on beam shape, and though nongaussian beams are being seriously
considered for advanced LIGO, no published analysis exists to compare the
quantitative thermal noise improvement alternate beams offer. In this paper, we
derive and discuss a simple integral which completely characterizes the
dependence of coating thermal noise on shape. The derivation used applies
equally well, with minor modifications, to all other forms of thermal noise in
the low-frequency limit.Comment: 3 pages. Originally performed in August 2004. Submitted to CQG. (v2)
: Corrections from referee and other
The GEO600 squeezed light source
The next upgrade of the GEO600 gravitational wave detector is scheduled for
2010 and will, in particular, involve the implementation of squeezed light. The
required non-classical light source is assembled on a 1.5m^2 breadboard and
includes a full coherent control system and a diagnostic balanced homodyne
detector. Here, we present the first experimental characterization of this
setup as well as a detailed description of its optical layout. A squeezed
quantum noise of up to 9dB below the shot-noise level was observed in the
detection band between 10Hz and 10kHz. We also present an analysis of the
optical loss in our experiment and provide an estimation of the possible
non-classical sensitivity improvement of the future squeezed light enhanced
GEO600 detector.Comment: 8 pages, 4 figure
The dependence of test-mass thermal noises on beam shape in gravitational-wave interferometers
In second-generation, ground-based interferometric gravitational-wave
detectors such as Advanced LIGO, the dominant noise at frequencies
Hz to Hz is expected to be due to thermal fluctuations in the
mirrors' substrates and coatings which induce random fluctuations in the shape
of the mirror face. The laser-light beam averages over these fluctuations; the
larger the beam and the flatter its light-power distribution, the better the
averaging and the lower the resulting thermal noise. In semi-infinite mirrors,
scaling laws for the influence of beam shape on the four dominant types of
thermal noise (coating Brownian, coating thermoelastic, substrate Brownian, and
substrate thermoelastic) have been suggested by various researchers and derived
with varying degrees of rigour. Because these scaling laws are important tools
for current research on optimizing the beam shape, it is important to firm up
our understanding of them. This paper (1) gives a summary of the prior work and
of gaps in the prior analyses, (2) gives a unified and rigorous derivation of
all four scaling laws, and (3) explores, relying on work by J. Agresti,
deviations from the scaling laws due to finite mirror size.Comment: 25 pages, 10 figures, submitted to Class. Quantum Gra
Sensitivity Studies for Third-Generation Gravitational Wave Observatories
Advanced gravitational wave detectors, currently under construction, are
expected to directly observe gravitational wave signals of astrophysical
origin. The Einstein Telescope, a third-generation gravitational wave detector,
has been proposed in order to fully open up the emerging field of gravitational
wave astronomy. In this article we describe sensitivity models for the Einstein
Telescope and investigate potential limits imposed by fundamental noise
sources. A special focus is set on evaluating the frequency band below 10Hz
where a complex mixture of seismic, gravity gradient, suspension thermal and
radiation pressure noise dominates. We develop the most accurate sensitivity
model, referred to as ET-D, for a third-generation detector so far, including
the most relevant fundamental noise contributions.Comment: 13 pages, 7 picture
Scientific Potential of Einstein Telescope
Einstein gravitational-wave Telescope (ET) is a design study funded by the
European Commission to explore the technological challenges of and scientific
benefits from building a third generation gravitational wave detector. The
three-year study, which concluded earlier this year, has formulated the
conceptual design of an observatory that can support the implementation of new
technology for the next two to three decades. The goal of this talk is to
introduce the audience to the overall aims and objectives of the project and to
enumerate ET's potential to influence our understanding of fundamental physics,
astrophysics and cosmology.Comment: Conforms to conference proceedings, several author names correcte
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