2,230 research outputs found
Analysis of Parametric Oscillatory Instability in Power Recycled LIGO Interferometer
We present the analysis of a nonlinear effect of parametric oscillatory
instability in power recycled LIGO interferometer with the Fabry-Perot (FP)
cavities in the arms. The basis for this effect is the excitation of the
additional (Stokes) optical mode and the mirror elastic mode, when the optical
energy stored in the main FP cavity main mode exceeds the certain threshold and
the frequencies are related so that sum of frequencies of Stokes and elastic
modes are approximately equal to frequencyof main mode. The presence of
anti-Stokes modes (with frequency approximately equal to sum of frequencies of
main and elastic modes) can depress parametric instability. However, it is very
likely that the anti-Stokes modes will not compensate the parametric
instability completely.Comment: 9 pages, 2 figures. submitted to Physics Letters
Stroboscopic Variation Measurement
A new procedure of the linear position measurement which allows to obtain
sensitivity better than the Standard Quantum Limit and close to the Energetic
Quantum Limit is proposed and analyzed in details. Proposed method is based on
the principles of stroboscopic quantum measurement and variation quantum
measurement and allows to avoid main disadvantages of both these procedures.
This method can be considered as a good candidate for use as a local position
meter in the ``intracavity'' topologies of the laser gravitational-wave
antennae.Comment: 13 pages, 2 figures drawn in TeX and 2 figures in postscript,
misprint correcte
The "optical lever" intracavity readout scheme for gravitational-wave antennae
An improved version of the ``optical bar'' intracavity readout scheme for
gravitational-wave antennae is considered. We propose to call this scheme
``optical lever'' because it can provide significant gain in the signal
displacement of the local mirror similar to the gain which can be obtained
using ordinary mechanical lever with unequal arms. In this scheme displacement
of the local mirror can be close to the signal displacement of the end mirrors
of hypothetical gravitational-wave antenna with arm lengths equal to the
half-wavelength of the gravitational wave.Comment: 10 pages, 3 figure
Quantum limits and symphotonic states in free-mass gravitational-wave antennae
Quantum mechanics sets severe limits on the sensitivity and required
circulating energy in traditional free-mass gravitational-wave antennas. One
possible way to avoid these restrictions is the use of intracavity QND
measurements. We analyze a new QND observable, which possesses a number of
features that make it a promising candidate for such measurements and propose a
practical scheme for the realization of this measurement. In combination with
an advanced coordinate meter, this scheme makes it possible to lower
substantially the requirements on the circulating power.Comment: 21 pages, 2 figure
Corner reflectors and Quantum-Non-Demolition Measurements in gravitational wave antennae
We propose Fabry-Perot cavity with corner reflectors instead of spherical
mirrors to reduce the contribution of thermoelastic noise in the coating which
is relatively large for spherical mirrors and which prevents the sensitivity
better than Standard Quantum Limit (SQL) from being achieved in laser
gravitational wave antenna. We demonstrate that thermo-refractive noise in
corner reflector (CR) is substantially smaller than SQL. We show that the
distortion of main mode of cavity with CR caused by tilt and displacement of
one reflector is smaller than for cavity with spherical mirrors. We also
consider the distortion caused by small nonperpendicularity of corner facets
and by optical inhomogeneity of fused silica which is proposed as a material
for corner reflectors.Comment: 12 pages, LaTex, 7 figure
Frequency-dependent rigidity in large-scale interferometric gravitational-wave detectors
Electromagnetic rigidity which exists in large-scale optical resonators if
pumping frequency is detuned from the eigenfrequency of resonator have
sophisticated spectral dependence which allows to obtain sensitivity better
than the Standard Quantum Limits both for the free test mass and the harmonic
oscillator.Comment: 11 pages, 6 figures, corrected typo
Measurements of the optical mirror coating properties
The results of measurement of optical mirror coating are presented. These
results indicate that Standard Quantum Limit of sensitivity can be reached in
the second stage of LIGO project if it is limited by thermoelastic noise in the
coating only.Comment: 5 page
Thermodynamical fluctuations in optical mirror coatings
Thermodynamical fluctuations of temperature in mirrors may produce surface
fluctuations not only through thermal expansion in mirror body but also through
thermal expansion in mirror coating. We analyze the last "surface" effect which
can be larger than the first "volume" one due to larger thermal expansion
coefficient of coating material and smaller effective volume. In particular,
these fluctuations may be important in laser interferometric gravitational
antennae.Comment: 12 pages, LaTex, 3 figure
Thermodynamical fluctuations and photo-thermal shot noise in gravitational wave antennae
Thermodynamical fluctuations of temperature in mirrors of gravitational wave
antennae are transformed through thermal expansion coefficient into additional
noise. This source of noise, which may also be interpreted as fluctuations due
to thermoelastic damping, may not be neglected and leads to the necessity to
reexamine the choice of materials for the mirrors. Additional source of noise
are fluctuations of the mirrors' surfaces caused by optical power absorbed in
dielectrical reflective layers.Comment: 20 pages, 2 figure
Interaction of plane gravitational waves with a Fabry-Perot cavity in the local Lorentz frame
We analyze the interaction of plane '+'-polarized gravitational waves with a
Fabry-Perot cavity in the local Lorentz frame of the cavity input mirror
outside of the range of long-wave approximation with the force of radiation
pressure taken into account. The obtained detector response signal is
represented as a sum of two parts: (i) the phase shift due to displacement of
the movable mirror under the influence of gravitational wave and the force of
light pressure, and (ii) the phase shift due to direct interaction of
gravitational wave with light wave inside the cavity. We obtain formula for the
movable mirror law of motion paying close attention to the phenomena of optical
rigidity, radiative friction and direct coupling of gravitational wave to light
wave. Some issues concerning the detection of high-frequency gravitational
waves and the role of optical rigidity in it are discussed. We also examine in
detail special cases of optical resonance and small detuning from it and
compare our results with the known ones.Comment: 17 pages, 9 figures; corrected references [7,8,34], added 2 new
references (currently [35,36]), added comments on (i) relativistic
corrections, (ii) detector angular pattern, (iii) quantized electromagnetic
field, increased font in figure
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