This manuscript derives explicit factors linking mode-mismatch-induced power losses, in Hermite-Gauss optical modes to the losses of the fundamental spatial mode. Higher order modes are found to be more sensitive to beam parameter mismatches. This is
particularly relevant for gravitational-wave detectors, where lasers employing higher-order optical modes have been proposed to mitigate thermal noise and quantum-enhanced detectors are very susceptible to losses. This work should inform mode matching and squeezing requirements for textit{Advanced+} and textit{Third Generation} detectors.
Advanced gravitational-wave detectors are limited by quantum noise in their most sensitive frequency band. Quantum noise suppression techniques, such as the application of the quantum squeezed state of light, have been actively studied in the context
of homodyne readouts. In this paper, we consider quantum squeezing schemes for the heterodyne readouts. This is motivated by a successful suppression of the higher-order-mode content by stable recycling cavities in advanced detectors. The heterodyne readout scheme requires precise tuning of the interferometer parameters and a broadband squeezing source, but is conceptually simple and elegant. We further show that it is compatible with the frequency-dependent squeezing, which reduces both the shot noise and the radiation-pressure noise. We propose a test of the heterodyne readout with squeezing in Advanced LIGO. This can serve as a pathfinder not only for the implementation in future detectors, such as Einstein Telescope and Cosmic Explorer, but also for general high-precision optical measurements.
We propose a new optical configuration for an interferometric gravitational wave detector based on the speedmeter concept using a sloshing cavity. Speedmeters provide an inherently better quantum-noise limited sensitivity at low frequencies than the
currently used Michelson interferometers. We show that a practical sloshing cavity can be added relatively simply to an existing dual-recycled Michelson interferometer such as Advanced LIGO.
This note describes the analytical derivation of the response of bullseye detectors to optical beats between higher-order spatial modes of the Laguerre-Gauss form, and subsequently the Hermite-Gauss form. Also included is a comparison with numericall
y calculated beat coefficients, and a simple example of the use of the resulting beat coefficients in simulating a mode mismatch sensor for a Fabry-Perot cavity.
This document records the results of a comparison of the interferometer simulation Finesse against an analytic (MATLAB based) calculation of the alignment sensing signals of a Fabry Perot cavity. This task was started during the commissioning worksho
p at the LIGO Livingston site between the 28.1. and 1.02 2013 with the aim of creating a reference example for validating numerical simulation tools. The FFT based simulation OSCAR joined the battle later.
A comparison of analytic calculations and FINESSE simulations of interferometer responses to gravitational wave strain. The response to a gravitational wave is gradually built up from the effect of modulating a space by a gravitational wave to Sagnac
and Michelson interferometers with and without arm cavities. This document details the steps necessary to perform such simulations in FINESSE and explicitly derives the interferometer response equations.
Finesse is a fast interferometer simulation program. For a given optical setup, it computes the light field amplitudes at every point in the interferometer assuming a steady state. To do so, the interferometer description is translated into a set of
linear equations that are solved numerically. For convenience, a number of standard analyses can be performed automatically by the program, namely computing modulation-demodulation error signals, transfer functions, shot-noise-limited sensitivities, and beam shapes. Finesse can perform the analysis using the plane-wave approximation or Hermite-Gauss modes. The latter allows computation of the properties of optical systems like telescopes and the effects of mode matching and mirror angular positions.
Several km-scale gravitational-wave detectors have been constructed world wide. These instruments combine a number of advanced technologies to push the limits of precision length measurement. The core devices are laser interferometers of a new kind;
developed from the classical Michelson topology these interferometers integrate additional optical elements, which significantly change the properties of the optical system. Much of the design and analysis of these laser interferometers can be performed using well-known classical optical techniques; however, the complex optical layouts provide a new challenge. In this review we give a textbook-style introduction to the optical science required for the understanding of modern gravitational wave detectors, as well as other high-precision laser interferometers. In addition, we provide a number of examples for a freely available interferometer simulation software and encourage the reader to use these examples to gain hands-on experience with the discussed optical methods.
