Real-time simulation of interferometric gravitational wave detectors involving moving mirrors

A method of real-time dynamical simulation for laser interferometric gravitational wave detectors is presented. The method is based on a digital filtering approach and a number of important physical points understood by a step-by-step investigation of two-mirror cavities, a three-mirror coupled cavity, and a full-length power-recycled interferometer with mirrors having longitudinal motion. The final analytical representation used for the fast simulation of a full-length power-recycled interferometer is analogous to a two-mirror dynamical cavity with time-dependent reflectivities, when intracavity fields of the interferometer are expressed together in a state-vector representation. A detailed discussion establishes the relationships among physical effects pertaining to field evolution in two-mirror cavities and coupled cavities or to the full interferometer

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]

Numerical calculations of diffraction losses in advanced interferometric gravitational wave detectors

Knowledge of the diffraction losses in higher-order modes of large optical cavities is essential for predicting three-mode parametric photon-phonon scattering, which can lead to mechanical instabilities in long-baseline gravitational wave detectors. We explore different numerical methods in order to determine the diffraction losses of the higher-order optical modes. Diffraction losses not only affect the power buildup inside the cavity but also influence the shape and frequency of the mode, which ultimately affect the parametric instability gain. Results depend on both the optical mode shape (order) and the mirror diameter. We also present a physical interpretation of these results

Scalar waves in the Witten bubble spacetime

Massless scalar waves in the Witten bubble spacetime are studied. The timelike and angular parts of the separated Klein-Gordon equation are written in terms of hyperbolic harmonics characterized by the generalized frequency ω. The radial equation is cast into the Schrödinger form. The above mathematical formulation is applied to study the scattering problem, the bound states, and the corresponding stability criteria. The results confirm the concept of a bubble wall as a perfectly reflecting expanding sphere

Modified photon equation of motion as a test for the principle of equivalence

We have considered a modified equation of motion based on the principle of covariance. Some astronomical observations are used to place limits on the presence of the extra terms in the modified equation

Physics of interferometric gravitational wave detectors

The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave detector like LIGO is a complex, non-linear, coupled, dynamic system. This article summarizes various interesting design characteristics of these detectors and techniques that were implemented in order to reach and maintain its operating condition. Specifically, the following topics are discussed: (i) length sensing and control, (ii) alignment sensing and control and (iii) thermal lensing which changes the performance and operating point of the interferometer as the input power to LIGO is increased

Physics of interferometric gravitational wave detectors

The Caltech-MIT joint LIGO project is operating three long-baseline interferometers (one of 2 km and two of 4 km) in order to unambiguously measure the infinitesimal displacements of isolated test masses which convey the signature of gravitational waves from astrophysical sources. An interferometric gravitational wave detector like LIGO is a complex, non-linear, coupled, dynamic system. This article summarizes various interesting design characteristics of these detectors and techniques that were implemented in order to reach and maintain its operating condition. Specifically, the following topics are discussed: (i) length sensing and control, (ii) alignment sensing and control and (iii) thermal lensing which changes the performance and operating point of the interferometer as the input power to LIGO is increased

Physics of interferometric gravitational wave

physics pp. 645–66