91,703 research outputs found
All-reflective coupling of two optical cavities with 3-port diffraction gratings
The shot-noise limited sensitivity of Michelson-type laser interferometers
with Fabry-Perot arm cavities can be increased by the so-called power-recycling
technique. In such a scheme the power-recycling cavity is optically coupled
with the interferometer's arm cavities. A problem arises because the central
coupling mirror transmits a rather high laser power and may show thermal
lensing, thermo-refractive noise and photo-thermo-refractive noise. Cryogenic
cooling of this mirror is also challenging, and thus thermal noise becomes a
general problem. Here, we theoretically investigate an all-reflective coupling
scheme of two optical cavities based on a 3-port diffraction grating. We show
that power-recycling of a high-finesse arm cavity is possible without
transmitting any laser power through a substrate material. The power splitting
ratio of the three output ports of the grating is, surprisingly, noncritical
Quantum Noise in Differential-type Gravitational-wave Interferometer and Signal Recycling
There exists the standard quantum limit (SQL), derived from Heisenberg's
uncertainty relation, in the sensitivity of laser interferometer
gravitational-wave detectors. However, in the context of a full
quantum-mechanical approach, SQL can be overcome using the correlation of shot
noise and radiation-pressure noise. So far, signal recycling, which is one of
the methods to overcome SQL, is considered only in a recombined-type
interferometer such as Advanced-LIGO, LCGT, and GEO600. In this paper, we
investigated quantum noise and the possibility of signal recycling in a
differential-type interferometer. As a result, we found that signal recycling
is possible and creates at most three dips in the sensitivity curve of the
detector. Then, taking advantage of the third additional dip and comparing the
sensitivity of a differential-type interferometer with that of a
next-generation Japanese GW interferometer, LCGT, we found that SNR of inspiral
binary is improved by a factor of 1.43 for neutron star binary, 2.28 for 50
M_sun black hole binary, and 2.94 for 100 M_sun black hole binary. We also
found that power recycling to increase laser power is possible in our
signal-recycling configuration of a detector.Comment: 17 pages, submitted to Phys.Rev.
Broadband squeezing of quantum noise in a Michelson interferometer with Twin-Signal-Recycling
Twin-Signal-Recycling (TSR) builds on the resonance doublet of two optically
coupled cavities and efficiently enhances the sensitivity of an interferometer
at a dedicated signal frequency. We report on the first experimental
realization of a Twin-Signal-Recycling Michelson interferometer and also its
broadband enhancement by squeezed light injection. The complete setup was
stably locked and a broadband quantum noise reduction of the interferometers
shot noise by a factor of up to 4\,dB was demonstrated. The system was
characterized by measuring its quantum noise spectra for several tunings of the
TSR cavities. We found good agreement between the experimental results and
numerical simulations
Recycled Noise Rectification: A Dumb Maxwell's Daemon
The one dimensional motion of a massless Brownian particle on a symmetric
periodic substrate can be rectified by re-injecting its driving noise through a
realistic recycling procedure. If the recycled noise is multiplicatively
coupled to the substrate, the ensuing feed-back system works like a passive
Maxwell's daemon, capable of inducing a net current that depends on both the
delay and the autocorrelation times of the noise signals. Extensive numerical
simulations show that the underlying rectification mechanism is a resonant
nonlinear effect: The observed currents can be optimized for an appropriate
choice of the recycling parameters with immediate application to the design of
nanodevices for particle transport.Comment: 7 pages, 6 figure
Squeezing and Dual Recycling in Laser Interferometric Gravitational Wave Detectors
We calculate the response of an ideal Michelson interferometer incorporating
both dual recycling and squeezed light to gravitational waves. The photon
counting noise has contributions from the light which is sent in through the
input ports as well as the vacuum modes at sideband frequencies generated by
the gravitational waves. The minimum detectable gravity wave amplitude depends
on the frequency of the wave as well as the squeezing and recycling parameters.
Both squeezing and the broadband operation of dual recycling reduce the photon
counting noise and hence the two techniques can be used together to make more
accurate phase measurements. The variance of photon number is found to be
time-dependent, oscillating at the gravity wave frequency but of much lower
order than the constant part.Comment: Plain tex, 11 pages, 1 figure available on request from
[email protected]
Demonstration of detuned dual recycling at the Garching 30m laser interferometer
Dual recycling is an advanced optical technique to enhance the
signal-to-noise ratio of laser interferometric gravitational wave detectors in
a limited bandwidth. To optimise the center of this band with respect to
Fourier frequencies of expected gravitational wave signals detuned dual
recycling has to be implemented. We demonstrated detuned dual recycling on a
fully suspended 30m prototype interferometer. A control scheme that allows to
tune the detector to different frequencies will be outlined. Good agreement
between the experimental results and numerical simulations has been achieved.Comment: 9 page
Resonant speed meter for gravitational wave detection
Gravitational-wave detectors have been well developed and operated with high
sensitivity. However, they still suffer from mirror displacement noise. In this
paper, we propose a resonant speed meter, as a displacement noise-canceled
configuration based on a ring-shaped synchronous recycling interferometer. The
remarkable feature of this interferometer is that, at certain frequencies,
gravitational-wave signals are amplified, while displacement noises are not.Comment: 4 pages, 4 figure
Optical noise correlations and beating the standard quantum limit in advanced gravitational-wave detectors
The uncertainty principle, applied naively to the test masses of a
laser-interferometer gravitational-wave detector, produces a Standard Quantum
Limit (SQL) on the interferometer's sensitivity. It has long been thought that
beating this SQL would require a radical redesign of interferometers. However,
we show that LIGO-II interferometers, currently planned for 2006, can beat the
SQL by as much as a factor two over a bandwidth \Delta f \sim f, if their
thermal noise can be pushed low enough. This is due to dynamical correlations
between photon shot noise and radiation-pressure noise, produced by the LIGO-II
signal-recycling mirror.Comment: 12 pages, 2 figures; minor changes, some references adde
- …